Slippery elm bark, the inner layer is the part used.

Herbs & Botanicals · Herbs · Soothing inner bark, with low-certainty evidence and little human research

Slippery Elm

Q: What is slippery elm?

Slippery elm (Ulmus rubra, also called red elm; the older name Ulmus fulva is the same tree) is a North American tree. The inner bark is dried and powdered. Mixed with water it makes a slippery gel called mucilage, which is why it has long been used as a soothing remedy for sore throat and an upset stomach.

Q: Does slippery elm help a sore throat?

Possibly for a short time, but we cannot say that slippery elm itself does it. One trial of 60 adults found a multi-herb tea that contains slippery elm eased throat pain for about 30 minutes after the first drink more than a placebo tea did. No trial tested slippery elm alone. Certainty is low.

Q: Does slippery elm help a cough or a cold?

Not shown. It is traditionally used for coughs, but we found no human trial for cough or colds. Memorial Sloan Kettering says there is no evidence it treats infections.

Q: Can slippery elm help heartburn or acid reflux?

It is a popular home remedy, but there is no trial of slippery elm alone. A review of popular reflux remedies lists it among herbs with a gap between stories and proof. A small uncontrolled study of a seven-ingredient blend reported fewer symptoms, but a blend cannot show what slippery elm does.

Q: Does it work for irritable bowel syndrome or constipation?

Unclear. In a small open study, a blend of slippery elm, lactulose, oat bran and licorice root was followed by more frequent, softer stools in 10 people with constipation-type IBS. The other ingredients can ease constipation by themselves, and there was no placebo group.

Q: Is slippery elm useful for Crohn disease or ulcerative colitis?

There is no trial in people. In a laboratory, extract calmed oxygen radicals in colitis tissue. That is a reason to study it, not proof that it helps. Do not use it in place of your IBD medicines.

Q: Does slippery elm treat cancer?

No. Memorial Sloan Kettering says there is no evidence it treats cancer. Slippery elm is one of the four herbs in Essiac tea; a study of 510 women with breast cancer found Essiac users did not have better quality of life.

Q: Can slippery elm affect my other medicines?

Possibly. The gel-like mucilage could slow or reduce how much of a swallowed medicine your body absorbs. WebMD says it may affect absorption of some medicines, but this has not been measured in a study, and another reference says there are no known severe interactions. Ask a pharmacist about timing, especially for thyroid, blood-thinning, seizure or heart medicines.

Q: Is slippery elm safe to take?

The US LiverTox entry says slippery elm preparations are generally recognized as safe and found no evidence of liver injury. Allergic reactions are possible, and one case report links an Ulmus rubra-rich product to a rare allergy-type bowel inflammation. Long-term safety has not been studied.

Q: Is slippery elm safe in pregnancy or while breastfeeding?

It is best avoided. WebMD says its effects in pregnancy and breast milk are not known. RxList states that whole bark is an abortifacient that may cause miscarriage, but shows no study for that claim, and we found no trial or case series of it with slippery elm taken by mouth. Ask your doctor.

Ulmus rubra Muhl. (also written Ulmus fulva Michx.) · also called Slippery elm, red elm, gray elm, soft elm, Rot-Ulme (German), orme rouge (French)

Slippery elm is an elm tree of eastern North America. Its dried inner bark makes a slippery gel when mixed with water. This gel, called mucilage, is the reason it is traditionally taken as a bark drink, powder or lozenge to soothe the throat and gut.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Slippery Elm

Slippery elm (Ulmus rubra) is a North American tree whose inner bark makes a soothing gel. It is used for sore throat, cough and gut upset, mostly by tradition. The only human data are one small trial of a multi-herb tea for sore throat, uncontrolled studies of blends for bowel and stomach symptoms, and an observational study of Essiac. The safest reading is a gentle traditional remedy with unproven benefits and a few cautions.

What it is

Slippery elm is Ulmus rubra, a tree in the elm family. The older name Ulmus fulva is the same tree. The inner bark is dried and ground to a powder.

The bark is rich in mucilage. In water it forms a slippery gel, which is the basis of the traditional idea that it coats and soothes the throat and gut. That coating has not been measured in people.

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What the research shows

One double-blind trial of 60 adults found a multi-herb tea that contains slippery elm eased sore throat pain for a short time more than a placebo tea. We found no trial of slippery elm alone.

For bowel and stomach problems, studies tested blends: a small open study in irritable bowel syndrome, a seven-ingredient gut formula, and a detox blend that did nothing. A cohort of women with breast cancer found no benefit from Essiac. Laboratory studies show antioxidant and antibacterial activity, but a dish is not a body.

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Amounts

This page does not give amounts. Ask a doctor or pharmacist what suits you.

At a glance

Traditional uses history, not proof

Sore throat and cough: bark drink or lozenge.
Gut upset and irritation: bark powder in water.
Skin rash, irritation and sores: a paste applied to the skin.
One of the four herbs in Essiac tea.

Studied for research

Sore throat: short relief in one trial of a multi-herb tea, low
Irritable bowel syndrome with constipation: open study of a blend, very low
Heartburn and indigestion: only blends, very low
Inflammatory bowel disease, skin and cancer: no human proof

Main compounds

Mucilage, a gel-forming fibre made of sugars
Galactose-based sugars in the mucilage
Tannins (gallic and tannic acid) found in some barks

Common forms

Inner-bark powder mixed with water
Lozenges
Herbal teas and blends
Poultice for the skin

Research links: LiverTox: Slippery Elm (US National Institutes of Health) · Throat Coat sore throat trial (abstract) · Memorial Sloan Kettering: Slippery Elm · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Ulmus rubra Muhl. (slippery elm, red elm)
Naming authority: Muhlenberg (GBIF lists the author as Muhl.). Ulmus fulva Michx. is a synonym (GBIF key 5361868).
Synonyms: Ulmus fulva Michx.
Common names: Slippery elm (English); Red elm (English); Gray elm (English); Soft elm (English); Rot-Ulme (German); Orme rouge (French); Orme gras (French); Rode iep (Dutch)
Botanical family: Ulmaceae (elm family, order Rosales).
Classification: Plantae > Tracheophyta > Magnoliopsida > Rosales > Ulmaceae > Ulmus > Ulmus rubra
Native range: Eastern North America (Wikipedia: southeastern North Dakota east to Maine and southern Quebec, south to northern Florida, west to eastern Texas). NOT verified from a primary source.
Habitat: Not verified in a source read. Wikipedia says moist uplands, tolerates dry soils (NOT verified).
What the plant looks like: Roots: Not part of medicinal use.; Stems: Inner bark (the layer under the outer bark) is the medicinal part; it is mucilaginous and edible per Wikipedia (NOT verified).; Leaves: Dried ground leaves can be made into tea per Wikipedia (NOT verified); not the studied part.; Flowers: Not described in sources read.; Fruit: Not described in sources read.
Cultivation: United Plant Savers: cultivation efforts have been sporadic and inadequate, cultivated bark is a small share of the trade (under 10,000 lb in AHPA surveys), and there are no published scientific growing trials.
Harvest and processing: UPS: bark is usually taken from trees or branches over one inch across, peels most easily late March to early June, is usually "rossed" (outer bark scraped off), and should be dried within a week. Thin vertical strips are recommended because girdling kills the tree.
Look-alikes and adulterants: Name: American elm (Ulmus americana); Note: Another native elm. UPS says slippery elm succumbs to many of the same diseases as American elm. Whether American elm bark is substituted in products was not found.; Name: Siberian elm (Ulmus pumila); Note: A non-native, invasive elm; one 2010 paper in the search results studies its hybridisation. Whether it appears in slippery elm products was not found.; Name: Old name Ulmus fulva; Note: Same species. Labels using it are not a different plant.
Sustainability and conservation: IUCN Least Concern (Wikipedia, citing Stritch 2018; NOT verified). United Plant Savers At-Risk List because of reliance on wild harvest. Wikipedia says it is reputedly less susceptible to Dutch elm disease than other American elms; UPS says Dutch elm disease and elm yellows are killing it.

The plant and the parts used

Close-up of slippery elm bark — Slippery elm bark, the inner layer is the part used.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
North America, traditional use	Inner bark used as a drink or paste for sore throat, cough, gut upset and skin sores (Memorial Sloan Kettering; LiverTox). Essiac, a four-herb tea that includes it, is described as reportedly developed by the Ojibwa people of Canada.	s-mskcc-slippery-elm
19th century surgery (1837 title)	PubMed lists a paper on slippery elm bark used for surgical bougies, tents and catheters (1837), apparently because the bark swells when wet. Only the title was seen.	p38080966
Mid-20th century laboratory chemistry	1946 and 1950 chemistry papers analysed the bark mucilage and found a methylated galactose sugar among its breakdown products (titles only).	p15400433
Modern market	Sold as powder, capsules, lozenges and in teas; the herbal tea Throat Coat lists slippery elm bark second in its current ingredients. Wild-harvested bark was 78,000 to 353,000 lb a year (AHPA surveys 1999-2010).	s-ups-slippery-elm-burkhart
Modern regulation	WebMD says the FDA has not reviewed it. Sold over the counter in the US as a demulcent per Wikipedia (NOT verified). No EU herbal monograph found.	s-webmd-slippery-elm

Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.

What is inside, and how it may work

What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Mucilage (galactose- and other-sugar polysaccharide)	polysaccharide / soluble fibre	Inner bark	Forms a gel with water; the traditional basis of the demulcent (soothing, coating) use. Not measured in people. ^{7 8}	Laboratory research
D-Galactose (sugar unit of the mucilage) PubChem 6036	monosaccharide	Inner bark mucilage	A 1950 paper title reports a methylated form (3-methyl D-galactose) from the mucilage breakdown; amounts not read. ⁸	Laboratory research
Tannins (for example gallic acid CID 370, tannic acid CID 16129778)	polyphenols	Bark	The KCNQ5 paper says gallic acid and tannic acid are common to the active barks tested; it does not say how much slippery elm contains. ¹³	Laboratory research

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Demulcent (coating) action of mucilage	None identified	Not measured. The explanation is that the gel coats irritated throat and gut lining. ²⁵	Pharmacological theory
Radical scavenging	Superoxide, peroxyl radicals, peroxynitrite	Extracts scavenged radicals in test tubes and reduced oxygen radicals from colitis biopsies in a dish. ^{10 6}	Laboratory research
Antibacterial action against Streptococcus pyogenes	Bacterial cell wall and membrane	Ethanol extract of inner bark: MIC 62.5 microgram/mL, MBC 125 microgram/mL in the laboratory (the abstract notes cell wall degradation for the four most effective extracts). ²¹	Laboratory research
Gut bacteria fermentation	Butyrate-producing bacteria	Ulmus rubra raised butyrate-producing bacteria in stool cultures. ¹⁵	Laboratory research
Potassium channel activation	KCNQ5 (voltage-gated potassium channel)	1% slippery elm bark extract strongly activated KCNQ5 in frog eggs; arteries not shown for slippery elm. ¹³	Laboratory research

Absorption, metabolism and elimination

Absorption: No human data on absorption of any slippery elm compound.
Distribution: No data.
Metabolism: No human data. Stool culture work shows gut bacteria change in the presence of Ulmus rubra.
Elimination: No data.
Bioavailability: Not established.

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Isolated compounds versus whole extracts

No single compound has been shown to explain the traditional effects. The leading idea is the whole mucilage gel, which only works as a gel, so isolated sugars would not do the same.

Nutritional composition

Slippery elm bark powder is a fibre-rich plant food but no nutrient table was read, so none is given here.

15benefits and uses looked at

31studies and sources checked

Low certaintybest evidence rating found

13lab markers tracked in trials

2 low certainty8 very low certainty4 not enough evidence1 evidence against

What was looked at

The 15 benefits and uses checked for Slippery Elm, each with how strong the evidence is. Tap one to open it.

Sore throat (pharyngitis): short-term pain reliefLow certainty
Cough, bronchitis and coldsNot enough evidence
Activity against strep throat bacteria (laboratory only)Very low certainty
Heartburn and acid reflux (GERD)Not enough evidence
Indigestion and upper-gut symptoms (seven-ingredient formula)Very low certainty
Antioxidant activity of slippery elm bark (laboratory only)Very low certainty
Irritable bowel syndrome with constipation (mixed-herb formula)Very low certainty
Constipation or diarrhoea on its ownNot enough evidence
Crohn disease and ulcerative colitisVery low certainty
Gut lining leakiness and gut bacteriaVery low certainty
Detox, body composition and waist sizeLow certainty
Skin irritation, rash and sores (poultice)Not enough evidence
Psoriasis (inside a whole-diet programme)Very low certainty
Cancer: Essiac herbal tea (a formula that contains slippery elm)Evidence against
Blood vessel relaxation (cell and animal tissue only)Very low certainty

Lab markers tracked in the studies

Throat pain on swallowingBacterial growth stopped in a dish (MIC and MBC)Digestive symptom questionnaire scoresUse of proton pump inhibitor medicinesFree radical scavenging in the laboratoryBowel movement frequencyStool consistencyAbdominal pain, bloating and strainingIntestinal permeability (lactulose-to-mannitol ratio)Gut bacteria mixBody composition and waist circumferencePsoriasis severity scores (PASI, PSS)Health-related quality of life in breast cancer (FACT-B)

What is Slippery Elm good for?

The main proposed uses and how strong the human evidence is for each. Nothing is above low certainty, and most results come from blends of several herbs.

Sore throat (pharyngitis): short-term pain reliefLow certaintyOne trial of a multi-herb tea that contains slippery elm eased throat pain for a short time. It cannot tell us what slippery elm does on its own. Throat pain on swallowing fell more with the tea than with placebo tea over the first 30 minutes after one dose. Relief was temporary. Cough, bronchitis and coldsNot enough evidenceSlippery elm is traditionally used for cough and chest colds. No human trial of slippery elm alone for cough or colds was found. No human results for cough or colds. Activity against strep throat bacteria (laboratory only)Very low certaintyIn a laboratory dish an alcohol extract of slippery elm inner bark stopped the growth of the bacterium behind strep throat. This has not been tested in people. Minimum inhibitory concentration 62.5 microgram/mL and minimum bactericidal concentration 125 microgram/mL for the most effective extracts, including slippery elm inner bark. Heartburn and acid reflux (GERD)Not enough evidenceSlippery elm is a popular home remedy for heartburn, but no trial of it alone has been found. A review calls the evidence for it thin. Nothing measured for slippery elm alone. Indigestion and upper-gut symptoms (seven-ingredient formula)Very low certaintyIn an uncontrolled study, a powder with slippery elm and six other ingredients was followed by fewer stomach and bowel symptoms. Without a placebo group this does not show the formula works, and it says little about slippery elm. Symptom questionnaires improved after the formula compared with the control phase. Antioxidant activity of slippery elm bark (laboratory only)Very low certaintySlippery elm bark extracts mopped up reactive oxygen molecules in test tubes. This is a lab finding, not a health benefit shown in people. Dose-dependent scavenging reported; no numbers in the abstracts. Irritable bowel syndrome with constipation (mixed-herb formula)Very low certaintyIn a small open study, a powder with slippery elm, lactulose, oat bran and licorice root was followed by easier, more frequent bowel movements and less pain. The other ingredients could explain this on their own. Constipation-predominant group: more frequent, softer stools and fewer symptoms. Diarrhoea/mixed group: some symptoms eased, bowel habit not improved. Constipation or diarrhoea on its ownNot enough evidenceSlippery elm is traditionally used for both, but no trial tested it alone for either. Nothing measured for slippery elm alone. Crohn disease and ulcerative colitisVery low certaintyNo trial in people with inflammatory bowel disease was found. Only laboratory tests show slippery elm extract calms oxygen radicals in colitis tissue. In-dish antioxidant effect only. Gut lining leakiness and gut bacteriaVery low certaintyIn a dish, slippery elm changed the mix of bacteria in human stool samples. In a seven-ingredient formula study, tests of gut-lining leakiness and gut bacteria improved, but slippery elm cannot be credited. Lab: butyrate producers up. Formula study: permeability ratio and bacteria improved. Detox, body composition and waist sizeLow certaintyA "detox" blend containing slippery elm did nothing for body composition, waist size or bowel symptoms compared with placebo in healthy women. No difference from placebo. Skin irritation, rash and sores (poultice)Not enough evidenceSlippery elm is traditionally applied to skin as a soothing paste, but no human study was found. No human results for slippery elm on skin. Psoriasis (inside a whole-diet programme)Very low certaintyFive people with psoriasis improved on a diet programme that included slippery elm bark water. Slippery elm cannot be credited. Scores improved overall. Cancer: Essiac herbal tea (a formula that contains slippery elm)Evidence againstNo evidence that slippery elm or Essiac treats cancer. A study of women with breast cancer found no benefit to quality of life from Essiac. No benefit on quality of life. Blood vessel relaxation (cell and animal tissue only)Very low certaintyA cell-based test found slippery elm bark extract opens a potassium channel linked to smooth muscle relaxation. The artery test was not reported for slippery elm. Channel activation in a laboratory cell model only.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Sore throat (pharyngitis): short-term pain relief

Low certainty

One trial of a multi-herb tea that contains slippery elm eased throat pain for a short time. It cannot tell us what slippery elm does on its own.

3 studiesTea in the trial. Slippery elm is also sold as lozenges and powder; n…

Studies, doses and limits

What the trials found

One double-blind placebo-controlled trial of 60 adults with acute pharyngitis tested Throat Coat, a multi-herb demulcent tea (the current label lists slippery elm bark second after licorice root, alongside marshmallow root, wild cherry bark, fennel, cinnamon and orange peel; the 2003 recipe was not checked). Pain on swallowing was lower than with placebo tea for about 30 minutes after the first dose. We found no trial of slippery elm alone for sore throat. Memorial Sloan Kettering says slippery elm may ease a minor sore throat but human data are lacking.

Results

Throat pain on swallowing fell more with the tea than with placebo tea over the first 30 minutes after one dose. Relief was temporary.

Effect sizes as reported

SPID -43.8 versus -16.5 (p = 0.012); TOTPAR 53.6 versus 32.4 (p = 0.031). Mean differences with confidence intervals not given in the abstract.

Why this rating

One small trial (60 people) of a combination product, with short follow-up. The effect cannot be credited to slippery elm. The product maker may have funded or supplied the trial (not stated).

Form and dose studied

Tea in the trial. Slippery elm is also sold as lozenges and powder; none of those was tested alone.

Who was studied

Adults with a sore throat, 2 to 7 days of symptoms.

Limits

Multi-herb product. Licorice root is a main ingredient and has its own safety limits. Only a few minutes to an hour of relief was measured. A sore throat with fever, trouble swallowing or breathing needs a doctor.

Why researchers looked

Slippery elm bark and lozenges are an old American remedy for a sore, scratchy throat. The gel-like mucilage is thought to coat the throat.

Traditional use

Used by Native American peoples and later by settlers as a bark tea and lozenge for sore throat and cough (traditional use; Memorial Sloan Kettering describes use for sore throat and cough).

Proposed mechanism Pharmacological theory

Slippery elm inner bark is rich in mucilage, a gel-forming plant fibre that coats the lining of the throat and gut when mixed with water. This coating idea (called a demulcent action) is the traditional explanation. It is a theory from how the material behaves; no study we read measured it in people.

A proposed mechanism does not show that the effect happens in people.

Allergy is possible. See the safety file for mixing with other medicines.

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Cough, bronchitis and colds

Not enough evidence

Slippery elm is traditionally used for cough and chest colds. No human trial of slippery elm alone for cough or colds was found.

2 studiesNot tested alone.

Studies, doses and limits

What the trials found

No clinical trial of slippery elm for cough, bronchitis or colds was found in PubMed. A 2024 review of traditional Iranian remedies lists slippery elm as an expectorant and an immune-stimulating plant but reports no trial for it. Memorial Sloan Kettering says there is no evidence it treats infections.

Results

No human results for cough or colds.

Effect sizes as reported

No numbers.

Why this rating

No human trials; the only support is traditional use and a literature list.

Form and dose studied

Not tested alone.

Limits

A review that lists traditional uses is not evidence that the plant works. Lab studies of alcohol extracts killing bacteria do not show a benefit from a swallowed tea.

Why researchers looked

The bark has long been taken as a soothing drink for dry coughs, and some traditional-medicine reviews list it among expectorant and immune-boosting plants.

Traditional use

Traditional use for cough and bronchitis (Memorial Sloan Kettering lists cough and bronchitis).

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

A cough lasting more than a few weeks, blood in phlegm, or breathlessness needs a doctor.

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Activity against strep throat bacteria (laboratory only)

Very low certainty

In a laboratory dish an alcohol extract of slippery elm inner bark stopped the growth of the bacterium behind strep throat. This has not been tested in people.

1 studiesEthanol extract of inner bark in the laboratory.

Studies, doses and limits

What the trials found

One laboratory study of 14 plant extracts. The authors picked sage leaf and purple coneflower flower as the most promising, not slippery elm.

Results

Minimum inhibitory concentration 62.5 microgram/mL and minimum bactericidal concentration 125 microgram/mL for the most effective extracts, including slippery elm inner bark.

Effect sizes as reported

MIC 62.5 microgram/mL; MBC 125 microgram/mL

Why this rating

Laboratory dish only; no animal or human data.

Form and dose studied

Ethanol extract of inner bark in the laboratory.

Who was studied

Bacteria in a dish.

Limits

A tea or lozenge in the mouth is not an alcohol extract at a measured concentration. Strep throat is a bacterial infection that can need antibiotics.

Why researchers looked

Researchers screened plant extracts for activity against Streptococcus pyogenes to find natural options for strep throat.

Traditional use

Not a traditional claim; a laboratory screen.

Proposed mechanism Laboratory research

Alcohol extracts of slippery elm inner bark damaged bacterial cell walls and membranes in the laboratory. The abstract names the four most effective extracts as licorice root, purple coneflower, sage leaf and slippery elm inner bark.

A proposed mechanism does not show that the effect happens in people.

Do not use slippery elm instead of a test and treatment for suspected strep throat (fever, swollen glands, no cough).

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Heartburn and acid reflux (GERD)

Not enough evidence

Slippery elm is a popular home remedy for heartburn, but no trial of it alone has been found. A review calls the evidence for it thin.

1 studiesNot tested alone.

Studies, doses and limits

What the trials found

A 2019 critical review of popular remedies for reflux and chest pain lists slippery elm among herbal products under study and says a large gap remains between anecdote and evidence. We found no trial of slippery elm alone for reflux. In a seven-ingredient formula that included slippery elm, heartburn improved in an uncontrolled study (see the next item).

Results

Nothing measured for slippery elm alone.

Effect sizes as reported

No numbers for slippery elm alone.

Why this rating

Only a review abstract naming slippery elm among other remedies; no controlled trial.

Form and dose studied

Not tested alone.

Limits

Only the review abstract was read. Heartburn that is frequent, or comes with trouble swallowing, weight loss, black stools or chest pain, needs a doctor.

Why researchers looked

The coating idea suggests slippery elm could soothe an irritated food pipe (oesophagus).

Traditional use

Folk use for stomach upset and gut irritation (LiverTox: sore throat and gastrointestinal upset).

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

Chest pain should never be put down to reflux without a check. Mucilage may slow the absorption of other medicines.

Indigestion and upper-gut symptoms (seven-ingredient formula)

Very low certainty

In an uncontrolled study, a powder with slippery elm and six other ingredients was followed by fewer stomach and bowel symptoms. Without a placebo group this does not show the formula works, and it says little about slippery elm.

1 studiesA powder taken at 5 g/day then 10 g/day (slippery elm amount not give…

Studies, doses and limits

What the trials found

43 adults completed a 16-week study with a control phase and then 5 g and 10 g a day for 4 weeks each. The authors report 60 to 80% improvement in symptom frequency and severity (indigestion, heartburn, nausea, constipation or diarrhoea, abdominal pain, wind) and that almost half of the people with upper-gut symptoms taking proton pump inhibitors no longer needed them by the end. There was no placebo group or blinding.

Results

Symptom questionnaires improved after the formula compared with the control phase.

Effect sizes as reported

Improvement of 60 to 80% (authors, abstract); almost half stopped proton pump inhibitors.

Why this rating

Uncontrolled, small, multi-ingredient, self-reported outcomes; slippery elm cannot be credited.

Form and dose studied

A powder taken at 5 g/day then 10 g/day (slippery elm amount not given in the abstract).

Who was studied

Adults with digestive disorders in Australia.

Limits

Never copy the stopping of acid-reducing medicines from this study; change medicines only with your doctor.

Why researchers looked

Researchers tested a ready-made gut-relief powder for people with digestive disorders.

Traditional use

Not a traditional product; a modern blend.

Proposed mechanism Pharmacological theory

Not studied for slippery elm separately. The formula also holds curcumin, aloe vera, guar gum, pectin, peppermint oil and glutamine, each with its own possible effects.

A proposed mechanism does not show that the effect happens in people.

Mucilage and fibres may change absorption of other medicines.

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Antioxidant activity of slippery elm bark (laboratory only)

Very low certainty

Slippery elm bark extracts mopped up reactive oxygen molecules in test tubes. This is a lab finding, not a health benefit shown in people.

2 studiesExtracts in a dish.

Studies, doses and limits

What the trials found

Test-tube and biopsy-tissue work only (see also the bowel file for the colitis biopsy study).

Results

Dose-dependent scavenging reported; no numbers in the abstracts.

Why this rating

Laboratory only.

Form and dose studied

Extracts in a dish.

Who was studied

Test tubes and tissue samples.

Limits

Antioxidant activity in a dish does not show a benefit in the body.

Why researchers looked

Free radicals made by inflamed tissue may add to damage, so researchers screen herbs for scavenging.

Traditional use

Not traditional.

Proposed mechanism Laboratory research

Slippery elm extract scavenged superoxide and peroxyl radicals in cell-free tests, reduced oxygen radical release from colitis biopsies in a dish, and ranked fifth for peroxynitrite scavenging among 28 herbs.

A proposed mechanism does not show that the effect happens in people.

None specific.

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Irritable bowel syndrome with constipation (mixed-herb formula)

Very low certainty

In a small open study, a powder with slippery elm, lactulose, oat bran and licorice root was followed by easier, more frequent bowel movements and less pain. The other ingredients could explain this on their own.

2 studiesPowdered mixtures; exact amounts not in the abstract.

Studies, doses and limits

What the trials found

One open-label, uncontrolled pilot study of 31 adults with IBS (Rome II). The constipation-predominant blend (slippery elm bark, lactulose, oat bran, licorice root; n=10) was followed by a 20% rise in bowel movement frequency, less straining, abdominal pain and bloating, and softer stools. A second blend with slippery elm for diarrhoea-predominant or mixed IBS (n=21) lifted some symptoms but did not improve bowel habit by the authors' own conclusion. There was no placebo group.

Results

Constipation-predominant group: more frequent, softer stools and fewer symptoms. Diarrhoea/mixed group: some symptoms eased, bowel habit not improved.

Effect sizes as reported

+20% bowel movement frequency (p = 0.016); straining p < 0.0001; abdominal pain p = 0.032; bloating p = 0.034 (C-IBS group)

Why this rating

Ten people in the constipation group, no control group, no blinding, and lactulose and oat bran are known to ease constipation. Slippery elm cannot be credited.

Form and dose studied

Powdered mixtures; exact amounts not in the abstract.

Who was studied

Adults with IBS in Australia.

Limits

Not a placebo-controlled trial. Licorice root in the blend has its own safety limits (blood pressure, potassium).

Why researchers looked

Slippery elm bark powder is often used by people with irritable bowel syndrome (IBS). Researchers tested two blends.

Traditional use

Traditional use for gut irritation and bowel regularity (Memorial Sloan Kettering lists constipation-predominant IBS in a formula).

Proposed mechanism Pharmacological theory

Slippery elm inner bark is rich in mucilage, a gel-forming plant fibre. Mixed with water it forms a slippery gel that is thought to coat and soothe the gut lining and to add soft bulk to stool. This is a theory from how the material behaves; no study we read measured these effects in people.

A proposed mechanism does not show that the effect happens in people.

Mucilage may change how other medicines are absorbed.

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Constipation or diarrhoea on its own

Not enough evidence

Slippery elm is traditionally used for both, but no trial tested it alone for either.

3 studiesNot tested alone.

Studies, doses and limits

What the trials found

No clinical trial of slippery elm alone for constipation or diarrhoea was found. The only data are inside multi-ingredient studies (IBS formulas and the seven-ingredient gut formula).

Results

Nothing measured for slippery elm alone.

Effect sizes as reported

No numbers.

Why this rating

No trials of slippery elm alone.

Form and dose studied

Not tested alone.

Limits

Persistent change in bowel habit, blood in stool, or weight loss needs a doctor.

Why researchers looked

Gel-forming fibre can soften and bulk stool, or firm loose stool, which is why mucilage herbs are used both ways.

Traditional use

Traditional use for bowel irregularity. Memorial Sloan Kettering says evidence is lacking for diarrhoea.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

Mucilage should be taken with enough water.

^{9 17 25}

Crohn disease and ulcerative colitis

Very low certainty

No trial in people with inflammatory bowel disease was found. Only laboratory tests show slippery elm extract calms oxygen radicals in colitis tissue.

2 studiesExtract applied to biopsies.

Studies, doses and limits

What the trials found

No human trial found. A laboratory study used cell-free tests and colon biopsies from people with active ulcerative colitis; a 2017 review of herb-drug interactions in older people with IBD lists Ulmus rubra among the herbs discussed, but the abstract does not give its findings.

Results

In-dish antioxidant effect only.

Effect sizes as reported

Dose-dependent scavenging; no numbers in abstract

Why this rating

Laboratory evidence only; the review abstract gave no slippery elm result.

Form and dose studied

Extract applied to biopsies.

Who was studied

Biopsies from active ulcerative colitis.

Limits

Antioxidant effects in tissue samples do not show that slippery elm controls IBD. Not a substitute for IBD medicines.

Why researchers looked

Many people with inflammatory bowel disease (IBD) try herbs, and slippery elm is one they report using.

Traditional use

Used by people with IBD as a bark powder or drink; no formal tradition for IBD.

Proposed mechanism Laboratory research

Extract reduced oxygen radical release from inflamed colon biopsies in a dish, similar to the medicine 5-ASA. The researchers say it merits formal trials.

A proposed mechanism does not show that the effect happens in people.

Mucilage may reduce the absorption of IBD medicines taken by mouth at the same time; talk to your gastroenterologist.

^{10 16}

Gut lining leakiness and gut bacteria

Very low certainty

In a dish, slippery elm changed the mix of bacteria in human stool samples. In a seven-ingredient formula study, tests of gut-lining leakiness and gut bacteria improved, but slippery elm cannot be credited.

2 studiesBark in culture; seven-ingredient formula at 5 and 10 g/day.

Studies, doses and limits

What the trials found

Laboratory fermentation of human stool with Ulmus rubra raised bacteria considered helpful and lowered some potential pathogens. In the uncontrolled formula study, most participants had a normal lactulose-to-mannitol permeability ratio at the end and Lactobacillus, Clostridium and Faecalibacterium prausnitzii rose; that product also contained guar gum, pectin and glutamine.

Results

Lab: butyrate producers up. Formula study: permeability ratio and bacteria improved.

Effect sizes as reported

No numbers in the abstracts.

Why this rating

One in-dish study plus an uncontrolled multi-ingredient study.

Form and dose studied

Bark in culture; seven-ingredient formula at 5 and 10 g/day.

Who was studied

Stool samples; 43 adults with digestive disorders.

Limits

Lab results do not show a health benefit. Permeability tests are not a settled measure of health.

Why researchers looked

Interest in a "leaky gut" and prebiotic effects of fibre-rich herbs.

Traditional use

Not traditional.

Proposed mechanism Laboratory research

Stool cultures grown in the laboratory with Ulmus rubra showed more butyrate-producing bacteria (butyrate is a fuel for the bowel lining).

A proposed mechanism does not show that the effect happens in people.

None specific.

^{15 17}

Detox, body composition and waist size

Low certainty

A "detox" blend containing slippery elm did nothing for body composition, waist size or bowel symptoms compared with placebo in healthy women.

1 studiesProprietary blend, 1,350 mg per serving, daily for 4 weeks.

Studies, doses and limits

What the trials found

One double-blind randomized trial of 22 healthy young women taking a proprietary blend of papaya leaf, cascara sagrada, slippery elm, peppermint, red raspberry leaf, fenugreek, ginger and senna leaf for four weeks found no benefit or harm on body composition, waist, bowel symptoms or blood safety markers.

Results

No difference from placebo.

Effect sizes as reported

No difference from placebo

Why this rating

A well-designed but tiny trial of a blend; null result.

Form and dose studied

Proprietary blend, 1,350 mg per serving, daily for 4 weeks.

Who was studied

Healthy young women.

Limits

Tiny trial in healthy women; says nothing about people with gut problems. The blend contains two stimulant laxatives (cascara, senna).

Why researchers looked

Slippery elm appears in many "cleanse" blends.

Traditional use

Not traditional.

Proposed mechanism Pharmacological theory

No mechanism was proposed in the abstract.

A proposed mechanism does not show that the effect happens in people.

Blends with cascara or senna can cause cramps, diarrhoea and low potassium.

¹⁹

Skin irritation, rash and sores (poultice)

Not enough evidence

Slippery elm is traditionally applied to skin as a soothing paste, but no human study was found.

2 studiesNot tested.

Studies, doses and limits

What the trials found

No clinical trial of slippery elm on the skin was found. Memorial Sloan Kettering says the mucilage is thought to be soothing but human data are lacking. In a five-person psoriasis case series, slippery elm bark water was drunk as part of a whole-diet programme, so it cannot be credited.

Results

No human results for slippery elm on skin.

Effect sizes as reported

No numbers.

Why this rating

No trials.

Form and dose studied

Not tested.

Limits

Do not put it on broken or infected skin or open wounds without medical advice; the skin can react.

Why researchers looked

Mucilage is soft and gel-like, so the powder is mixed with water and used as a poultice.

Traditional use

LiverTox and Memorial Sloan Kettering list topical use for rash, irritation and skin ulcers.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

Allergic skin reaction is possible.

^{25 12}

Psoriasis (inside a whole-diet programme)

Very low certainty

Five people with psoriasis improved on a diet programme that included slippery elm bark water. Slippery elm cannot be credited.

1 studiesSlippery elm bark water daily as part of the programme.

Studies, doses and limits

What the trials found

In five adults the average psoriasis score (PASI) went from 18.2 to 8.7 and the permeability ratio from 0.066 to 0.026 over six months. There was no control group and the plan changed diet, fibre, oils and teas at the same time.

Results

Scores improved overall.

Effect sizes as reported

PASI 18.2 to 8.7; PSS 14.6 to 5.4 (averages of five people)

Why this rating

Five people, no control, many changes at once.

Form and dose studied

Slippery elm bark water daily as part of the programme.

Who was studied

Five adults with chronic plaque psoriasis.

Limits

Do not read this as slippery elm treating psoriasis.

Why researchers looked

A 10-day programme followed by six months of diet based on Edgar Cayce readings.

Traditional use

Not a standard traditional use.

Proposed mechanism Pharmacological theory

None proposed for slippery elm.

A proposed mechanism does not show that the effect happens in people.

None specific.

⁵

Cancer: Essiac herbal tea (a formula that contains slippery elm)

Evidence against

No evidence that slippery elm or Essiac treats cancer. A study of women with breast cancer found no benefit to quality of life from Essiac.

3 studiesEssiac (four-herb tea), about 44 mL a day on label directions.

Studies, doses and limits

What the trials found

A retrospective cohort of 510 Ontario women with breast cancer found Essiac users did not have better quality of life or mood and did slightly worse on two subscales, probably because they had more advanced disease; only 2 women reported minor adverse events. Memorial Sloan Kettering says there is no evidence slippery elm treats cancer.

Results

No benefit on quality of life.

Effect sizes as reported

No benefit

Why this rating

The best human study found no benefit; laboratory antioxidant work is not a treatment effect.

Form and dose studied

Essiac (four-herb tea), about 44 mL a day on label directions.

Who was studied

Women with breast cancer, Ontario.

Limits

Observational, four-herb blend, cannot say whether Essiac harms or helps outcomes.

Why researchers looked

Slippery elm bark is one of the four herbs in Essiac, a tea widely promoted as a cancer remedy.

Traditional use

Essiac is described as a formula reportedly developed by the Ojibwa and popularised in Canada (the abstract says "reportedly").

Proposed mechanism Laboratory research

Essiac tea scavenged free radicals and protected DNA in test tubes, which the authors say may help explain reports of anti-cancer effects.

A proposed mechanism does not show that the effect happens in people.

Essiac contains Indian rhubarb, a laxative plant. Tell your cancer team about any herbs.

^{22 11 25}

Blood vessel relaxation (cell and animal tissue only)

Very low certainty

A cell-based test found slippery elm bark extract opens a potassium channel linked to smooth muscle relaxation. The artery test was not reported for slippery elm.

1 studies1% bark extract in the laboratory.

Studies, doses and limits

What the trials found

No human data. In frog egg cells carrying the human channel, 1% slippery elm bark extract strongly activated it. Rat artery relaxation was shown for red willow, white willow and white oak, not reported for slippery elm.

Results

Channel activation in a laboratory cell model only.

Why this rating

Cells only.

Form and dose studied

1% bark extract in the laboratory.

Who was studied

Xenopus oocytes.

Limits

No evidence for any effect on blood pressure or cramps in people.

Why researchers looked

Researchers explored how bark remedies used for cramps might relax smooth muscle.

Traditional use

Bark remedies are used in Native American folk medicine for cramps.

Proposed mechanism Laboratory research

Bark tannins (gallic acid and tannic acid are named as common to the active barks) activated KCNQ5 channels; not shown for slippery elm specifically.

A proposed mechanism does not show that the effect happens in people.

None specific.

¹³

Connections to the rest of health

How Slippery Elm connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Calm Relaxation	Potential benefit	Low certainty	Sore throat (pharyngitis): short-term pain relief: One trial of a multi-herb tea that contains slippery elm eased throat pain for a short time. It cannot tell us what slippery elm does on its own.	^{4 28 25}
Immune Support	Traditional use	Not enough evidence	Cough, bronchitis and colds: Slippery elm is traditionally used for cough and chest colds. No human trial of slippery elm alone for cough or colds was found.	^{18 25}
Immune Support	Preliminary mechanism	Very low certainty	Activity against strep throat bacteria (laboratory only): In a laboratory dish an alcohol extract of slippery elm inner bark stopped the growth of the bacterium behind strep throat. This has not been tested in people.	²¹
Digestive Support	Traditional use	Not enough evidence	Heartburn and acid reflux (GERD): Slippery elm is a popular home remedy for heartburn, but no trial of it alone has been found. A review calls the evidence for it thin. Constipation or diarrhoea on its own: Slippery elm is traditionally used for both, but no trial tested it alone for either.	^{1 9 17 25}
Digestive Support	Potential benefit	Very low certainty	Indigestion and upper-gut symptoms (seven-ingredient formula): In an uncontrolled study, a powder with slippery elm and six other ingredients was followed by fewer stomach and bowel symptoms. Without a placebo group this does not show the formula works, and it says little about slippery elm. Irritable bowel syndrome with constipation (mixed-herb formula): In a small open study, a powder with slippery elm, lactulose, oat bran and licorice root was followed by easier, more frequent bowel movements and less pain. The other ingredients could explain this on their own.	^{17 9 25}
Gut Health	Potential benefit	Very low certainty	Indigestion and upper-gut symptoms (seven-ingredient formula): In an uncontrolled study, a powder with slippery elm and six other ingredients was followed by fewer stomach and bowel symptoms. Without a placebo group this does not show the formula works, and it says little about slippery elm. Irritable bowel syndrome with constipation (mixed-herb formula): In a small open study, a powder with slippery elm, lactulose, oat bran and licorice root was followed by easier, more frequent bowel movements and less pain. The other ingredients could explain this on their own.	^{17 9 25}
Inflammation Balance	Preliminary mechanism	Very low certainty	Antioxidant activity of slippery elm bark (laboratory only): Slippery elm bark extracts mopped up reactive oxygen molecules in test tubes. This is a lab finding, not a health benefit shown in people. Crohn disease and ulcerative colitis: No trial in people with inflammatory bowel disease was found. Only laboratory tests show slippery elm extract calms oxygen radicals in colitis tissue.	^{6 10 16}
Gut Health	Preliminary mechanism	Very low certainty	Crohn disease and ulcerative colitis: No trial in people with inflammatory bowel disease was found. Only laboratory tests show slippery elm extract calms oxygen radicals in colitis tissue. Gut lining leakiness and gut bacteria: In a dish, slippery elm changed the mix of bacteria in human stool samples. In a seven-ingredient formula study, tests of gut-lining leakiness and gut bacteria improved, but slippery elm cannot be credited.	^{10 16 15 17}
Weight Management	Demonstrated clinical effect	Low certainty	Detox, body composition and waist size: A "detox" blend containing slippery elm did nothing for body composition, waist size or bowel symptoms compared with placebo in healthy women.	¹⁹
Healthy Skin	Traditional use	Not enough evidence	Skin irritation, rash and sores (poultice): Slippery elm is traditionally applied to skin as a soothing paste, but no human study was found.	^{25 12}
Healthy Skin	Potential benefit	Very low certainty	Psoriasis (inside a whole-diet programme): Five people with psoriasis improved on a diet programme that included slippery elm bark water. Slippery elm cannot be credited.	⁵
Immune Support	Potential benefit	Evidence against	Cancer: Essiac herbal tea (a formula that contains slippery elm): No evidence that slippery elm or Essiac treats cancer. A study of women with breast cancer found no benefit to quality of life from Essiac.	^{22 11 25}
Blood Pressure Support	Preliminary mechanism	Very low certainty	Blood vessel relaxation (cell and animal tissue only): A cell-based test found slippery elm bark extract opens a potassium channel linked to smooth muscle relaxation. The artery test was not reported for slippery elm.	¹³

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Digestive system	Drug or supplement interaction	Not enough evidence	May change how swallowed medicines are absorbed; unmeasured. Mucilage may change absorption of other medicines (unmeasured). Preparation or compound: Mucilage	³⁰
Immune system	Adverse effect or risk	Low certainty	Allergic reaction; one case report of eosinophilic colitis. Preparation or compound: Ulmus rubra-rich product	^{3 30}
Reproductive system	Contraindication	Not enough evidence	Avoid in pregnancy; abortifacient claim from folk use, source not shown. Preparation or compound: Whole bark	^{27 30}
Respiratory System	Biological association	Low certainty	Studied for: Sore throat (pharyngitis): short-term pain relief Studied for: Cough, bronchitis and colds	^{4 28 25 18 21}
Digestive System	Biological association	Not enough evidence	Studied for: Heartburn and acid reflux (GERD) Studied for: Indigestion and upper-gut symptoms (seven-ingredient formula)	^{1 17 6 10 9 25 16 15}
Immune System	Biological association	Very low certainty	Studied for: Crohn disease and ulcerative colitis Studied for: Cancer: Essiac herbal tea (a formula that contains slippery elm)	^{10 16 22 11 25}
Metabolism Weight	Biological association	Low certainty	Studied for: Detox, body composition and waist size	¹⁹
Integumentary System	Biological association	Not enough evidence	Studied for: Skin irritation, rash and sores (poultice) Studied for: Psoriasis (inside a whole-diet programme)	^{25 12 5}
Cardiovascular System	Biological association	Very low certainty	Studied for: Blood vessel relaxation (cell and animal tissue only)	¹³

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Liver	Biological association	Authoritative guidance	LiverTox found no evidence of liver injury. No evidence of liver injury (LiverTox). Preparation or compound: Inner bark	¹²

D. Symptoms

Connected to	Kind of connection	Evidence status	Context	Studies
Sore throat	Potential benefit	Low certainty	Short relief in one trial of a multi-herb tea. Preparation or compound: Throat Coat tea (contains slippery elm)	⁴

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Throat pain on swallowing	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁴
Bacterial growth stopped in a dish (MIC and MBC)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	²¹
Digestive symptom questionnaire scores	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁷
Use of proton pump inhibitor medicines	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁷
Free radical scavenging in the laboratory	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{10 6}
Bowel movement frequency	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	⁹
Stool consistency	Biological association	Very low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	⁹
Abdominal pain, bloating and straining	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁹
Intestinal permeability (lactulose-to-mannitol ratio)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{17 5}
Gut bacteria mix	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	^{15 17}
Body composition and waist circumference	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	¹⁹
Psoriasis severity scores (PASI, PSS)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁵
Health-related quality of life in breast cancer (FACT-B)	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	²²

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
KCNQ5	Preliminary mechanism	In vitro	Activated by bark extracts in laboratory cells; slippery elm was among them.	¹³

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Oxidative stress (superoxide, peroxynitrite)	Preliminary mechanism	In vitro	Scavenging in test tubes.	^{10 6}
Butyrate-producing gut bacteria	Preliminary mechanism	In vitro	Raised in stool cultures with Ulmus rubra.	¹⁵

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Mucilage (galactose- and other-sugar polysaccharide)	Biological association	In vitro	Forms a gel with water; the traditional basis of the demulcent (soothing, coating) use. Not measured in people. Preparation or compound: Inner bark	^{7 8}
D-Galactose (sugar unit of the mucilage)	Biological association	In vitro	A 1950 paper title reports a methylated form (3-methyl D-galactose) from the mucilage breakdown; amounts not read. Preparation or compound: Inner bark mucilage	⁸
Tannins (for example gallic acid CID 370, tannic acid CID 16129778)	Biological association	In vitro	The KCNQ5 paper says gallic acid and tannic acid are common to the active barks tested; it does not say how much slippery elm contains. Preparation or compound: Bark	¹³

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 13 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Other8221

The evidence

The research centre for Slippery Elm. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Sore throat (pharyngitis): short-term pain relief 3 studies · 60 people in trials Low certainty Cough, bronchitis and colds 2 studies Not enough evidence Activity against strep throat bacteria (laboratory only) 1 study Very low certainty Heartburn and acid reflux (GERD) 1 study Not enough evidence Indigestion and upper-gut symptoms (seven-ingredient formula) 1 study Very low certainty Antioxidant activity of slippery elm bark (laboratory only) 2 studies Very low certainty Irritable bowel syndrome with constipation (mixed-herb formula) 2 studies Very low certainty Constipation or diarrhoea on its own 3 studies Not enough evidence Crohn disease and ulcerative colitis 2 studies Very low certainty Gut lining leakiness and gut bacteria 2 studies Very low certainty Detox, body composition and waist size 1 study · 22 people in trials Low certainty Skin irritation, rash and sores (poultice) 2 studies Not enough evidence Psoriasis (inside a whole-diet programme) 1 study · 5 people in trials Very low certainty Cancer: Essiac herbal tea (a formula that contains slippery elm) 3 studies Evidence against Blood vessel relaxation (cell and animal tissue only) 1 study Very low certainty

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We searched PubMed, read the abstracts of every study cited, read the US government LiverTox summary, the Memorial Sloan Kettering and WebMD and RxList pages, the United Plant Savers article and the current text of the main FDA cough and cold rule.

Study library: every study we checked 31

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
Ahuja 2019 Popular Remedies for Esophageal Symptoms: a Critical Appraisal. Curr Gastroenterol Rep · PMID 31289950 · DOI	Narrative review	Popular remedies for reflux and non-cardiac chest pain (review)	Dietary changes, apple cider vinegar, melatonin, acupuncture and herbal products including slippery elm, among others	The abstract lists slippery elm among several herbal products being researched for reflux and chest pain and says a substantial gap remains between anecdote and evidence for most non-drug remedies. It gives no result for slippery elm. No numbers given for slippery elm Methods, limits and funding Outcomes: Clinical use and mechanisms of popular remedies for oesophageal symptoms Limitations: Only the abstract was read. Narrative review, not a systematic one. Funding and conflicts: No conflict statement in the abstract. Read: abstract
Ainsworth-Davis 1932 A Piece of Slippery Elm Removed from the Bladder. Proc R Soc Med · PMID 19988576 · DOI	Case report	1 A patient with a piece of slippery elm found in the bladder (1932 case report)	Slippery elm (form not known; abstract not available) bark (presumed) Unknown Unknown	Only the title was read: a piece of slippery elm removed from the bladder. No abstract is available. None Methods, limits and funding Outcomes: Foreign body in the bladder Limitations: Only the title was seen. Funding and conflicts: Not stated. Read: summary-only
Amado 2021 Subserous Type of Eosinophilic Colitis: A Rare Disease. Eur J Case Rep Intern Med · PMID 34377693 · DOI	Case report	1 One woman with subserous eosinophilic colitis, Portugal	An Ulmus rubra-rich product (details not in abstract) bark (presumed)	The authors say the colitis was potentially triggered by taking an Ulmus rubra-rich product. They do not claim proof. Single case Methods, limits and funding Outcomes: Diagnosis and likely trigger of eosinophilic colitis Limitations: One person; a possible trigger is not proof; no re-challenge reported in the abstract. Funding and conflicts: No competing interests declared. Read: abstract
Brinckmann 2003 Safety and efficacy of a traditional herbal medicine (Throat Coat) in symptomatic temporary relief of pain in patients with acute pharyngitis: a multicenter, prospective, randomized, double-blinded, placebo-controlled study. J Altern Complement Med · PMID 12804082 · DOI	Controlled trial	60 Adults (18+) with acute pharyngitis (sore throat), three US primary care clinics	Throat Coat, a multi-herb demulcent tea (Traditional Medicinals); the abstract does not list the herbs, so the slippery elm share is unknown multi-herb (not stated in abstract) 5-8 oz, 4-6 times a day 2 to 7 days · vs Placebo tea	Pain on swallowing was lower with Throat Coat than with placebo tea at 5, 10, 15, 20 and 30 minutes after the first dose. SPID least-squares mean -43.8 (SEM 11.9) with Throat Coat versus -16.5 (SEM 13.9) with placebo (p = 0.012). TOTPAR 53.6 (SEM 10.9) versus 32.4 (SEM 12.8) (p = 0.031). Relief was temporary. SPID p = 0.012; TOTPAR p = 0.031 (valid-for-efficacy analysis) Methods, limits and funding Outcomes: Pain on swallowing: sum of pain intensity differences (SPID) and total pain relief (TOTPAR) over the first 30 minutes after the first dose Limitations: A combination tea, so the result cannot be credited to slippery elm. Small (60 people). Follow-up of only a few days. A warm drink and honey-like placebo effects are possible, and the placebo tea may not have matched the taste. Funding not stated in the abstract; the product belongs to the company named in the paper (Traditional Medicinals). Funding and conflicts: Funding not stated in the abstract. The trial tested a commercial product, so an industry link is likely but not confirmed. Read: abstract
Brown 2004 Medical nutrition therapy as a potential complementary treatment for psoriasis--five case reports. Altern Med Rev · PMID 15387720	Case series	5 Five adults with chronic plaque psoriasis, USA	A whole-diet programme based on Edgar Cayce readings (fruit and vegetables, fish and fowl, fibre supplements, olive oil, no red meat or processed foods) with daily saffron tea and slippery elm bark water bark (as drink, one part of a whole programme) 6 months	Average PASI 18.2 to 8.7 and PSS 14.6 to 5.4; permeability ratio 0.066 to 0.026. The authors call for more research. PASI 18.2 to 8.7 (average of 5 people) Methods, limits and funding Outcomes: Psoriasis Area and Severity Index, Psoriasis Severity Scale, lactulose/mannitol permeability Limitations: Five people, no control group, many changes at once (diet, supplements, a 10-day live-in programme). Slippery elm cannot be credited. Funding and conflicts: Not stated in the abstract. Read: abstract
Choi 2002 Peroxynitrite scavenging activity of herb extracts. Phytother Res · PMID 12112294 · DOI	Laboratory research in-vitro	Chemical tests on 28 herb extracts	Extracts of 28 herbs including slippery elm bark · vs Other herbs	Slippery elm was fifth in potency of those the abstract ranked (witch hazel bark > rosemary > jasmine tea > sage > slippery elm > black walnut leaf > Queen Anne's lace > linden flower). Rank 5 in the abstract list Methods, limits and funding Outcomes: Peroxynitrite scavenging Limitations: Test tube only. Funding and conflicts: Not stated in the abstract. Read: abstract
GILL 1946 Constitution of the mucilage from the bark of Ulmus fulva (slippery elm mucilage); the sugars formed in the hydrolysis of the methylated mucilage. J Chem Soc · PMID 20282480 · DOI	Chemistry in-vitro	Laboratory chemistry (1946)	Slippery elm bark mucilage, methylated and broken down bark	Only the title was read: it studies the sugars formed on hydrolysis of the methylated mucilage of Ulmus fulva bark. None Methods, limits and funding Outcomes: Sugars formed when the mucilage is broken down Limitations: Title only; no abstract. Funding and conflicts: Not stated. Read: summary-only
HOUGH 1950 Chemical constitution of slippery elm mucilage; isolation of 3-methyl d-galactose from the hydrolysis products. Nature · PMID 15400433 · DOI	Chemistry in-vitro	Laboratory chemistry (1950)	Slippery elm bark mucilage bark	Only the title was read: it reports isolating 3-methyl D-galactose from the hydrolysis products of slippery elm mucilage. None Methods, limits and funding Outcomes: Sugar content of the mucilage Limitations: Title only; no abstract. Funding and conflicts: Not stated. Read: summary-only
Hawrelak 2010 Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study. J Altern Complement Med · PMID 20954962 · DOI	Open label uncontrolled	31 Adults meeting Rome II criteria for irritable bowel syndrome (21 diarrhoea-predominant or alternating, 10 constipation-predominant), Australia, recruited 2001	Two powdered herbal formulas. DA-IBS: bilberry fruit, slippery elm bark, agrimony aerial parts, cinnamon quills. C-IBS: slippery elm bark, lactulose, oat bran, licorice root bark (plus other herbs and fibre)	C-IBS group (constipation-predominant, n=10): bowel movement frequency up 20% (p = 0.016); less straining (p < 0.0001), abdominal pain (p = 0.032), bloating (p = 0.034); better stool consistency (p < 0.0001). DA-IBS group (n=21): small rise in bowel frequency (p = 0.027) and fewer symptoms, but the authors say it was not effective for bowel habit in this group. C-IBS: +20% bowel movement frequency (p = 0.016) Methods, limits and funding Outcomes: Bowel movement frequency, stool consistency, straining, abdominal pain, bloating, flatulence, global IBS symptoms Limitations: Open-label with no control group, 31 people, only 10 in the constipation group. Both formulas are mixtures; lactulose and oat bran in C-IBS are known to ease constipation by themselves, so slippery elm cannot be credited. No blinding. Funding and conflicts: No funding statement in the abstract; first author is affiliated with a naturopathic practice. Read: abstract
Langmead 2002 Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study. Aliment Pharmacol Ther · PMID 11860402 · DOI	Laboratory research in-vitro	Cell-free chemical tests and biopsies from people with active ulcerative colitis	Extracts of slippery elm, fenugreek, devil's claw, Mexican yam, tormentil and wei tong ning; 5-ASA (mesalazine) for comparison bark · vs 5-ASA	All herbs except fenugreek scavenged superoxide in a dose-dependent way. All materials scavenged peroxyl radicals. Oxygen radical release from inflamed colon biopsies fell after incubation with all herbs except Mexican yam, and with 5-ASA. Dose-dependent scavenging; no numbers in abstract Methods, limits and funding Outcomes: Superoxide and peroxyl radical scavenging; oxygen radical release from colon biopsies Limitations: Laboratory test tubes and biopsy tissue only, not people taking the herb by mouth. Antioxidant activity in a dish does not show a benefit in the body. Funding and conflicts: No conflict statement in the abstract. Read: abstract
Leonard 2006 Essiac tea: scavenging of reactive oxygen species and effects on DNA damage. J Ethnopharmacol · PMID 16226859 · DOI	Laboratory research in-vitro	Test-tube chemistry and a mouse macrophage cell line	Essiac tea (burdock, sheep sorrel, Ulmus rubra and Indian rhubarb), boiled 25 mg/mL extract inner bark (one of four herbs) 5-50% dilutions of the tea	At the 50% preparation, signals of hydroxyl and superoxide radicals fell by up to 84% and 82%; hydroxyl-induced DNA damage was prevented and lipid peroxidation fell by up to 50%. Up to 84% (hydroxyl) and 82% (superoxide) lower radical signal Methods, limits and funding Outcomes: Free radical scavenging, DNA damage, lipid peroxidation Limitations: A four-herb tea in a dish. No human data. Funding and conflicts: Not stated in the abstract. Read: abstract
LiverTox (NIDDK) 2024 Slippery Elm. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (NIDDK), updated 5 Jan 2024 · PMID 38289993	Authoritative guidance	Reference entry on liver injury from herbs	Slippery elm (Ulmus rubra) inner bark preparations inner bark	LiverTox (NIDDK) says the inner bark is used by mouth for sore throat and stomach upset and on the skin for rash and irritation, that slippery elm preparations are generally recognized as safe, and that there is no evidence they cause raised liver enzymes or clinically apparent liver injury. No liver signal reported Methods, limits and funding Outcomes: Liver safety Limitations: Only the abstract was read. An absence of reports is not proof of safety. Funding and conflicts: Government reference. Read: abstract
Manville 2022 KCNQ5 activation by tannins mediates vasorelaxant effects of barks used in Native American botanical medicine. FASEB J · PMID 35997997 · DOI	Laboratory research in-vitro	Frog egg cells (Xenopus oocytes) carrying a human potassium channel, and rat arteries	Bark extracts (1%) of birch, cramp bark, slippery elm, white oak, red willow, white willow and wild cherry bark 1% extract · vs Other barks	Slippery elm bark extract strongly activated the KCNQ5 potassium channel in oocytes. The artery-relaxing tests were done only on red willow, white willow and white oak (they relaxed rat arteries); slippery elm was not reported as tested in arteries in the abstract. Not a human result Methods, limits and funding Outcomes: KCNQ5 channel activation; blood vessel relaxation Limitations: Cell and animal tissue only. Slippery elm was not shown to relax arteries. Funding and conflicts: Authors declare no competing interests. Read: abstract
McDowell 1837 Elm Bark in Surgery: An Account of the Use of the Bark of the Slippery Elm Tree (Ulmus Fulva), for Bougies, Tents, Catheters, and Similar Purposes in Surgery. West J Med Phys Sci · PMID 38080966	Historical article	Surgeons, 1837	Slippery elm bark swollen in water for surgical bougies, tents and catheters (title only) bark	Only the title and index record were seen: "Elm Bark in Surgery: An Account of the Use of the Bark of the Slippery Elm Tree (Ulmus Fulva), for Bougies, Tents, Catheters, and..." (title is cut off in the record). None Methods, limits and funding Outcomes: History of surgical use Limitations: Title only; historical context for the bladder case reports. Funding and conflicts: Not stated. Read: summary-only
Peterson 2018 Prebiotic Potential of Herbal Medicines Used in Digestive Health and Disease. J Altern Complement Med · PMID 29565634 · DOI	Laboratory research in-vitro	Human stool samples grown anaerobically in the laboratory	Ulmus rubra, Glycyrrhiza glabra (licorice) and triphala added to stool cultures bark · vs Unsupplemented cultures	Ulmus rubra and triphala significantly raised the relative abundance of butyrate-producing bacteria. The herbs raised many bacteria considered helpful (Bifidobacterium, Lactobacillus, Bacteroides) and lowered some potential pathogens in the dish. No numbers in abstract Methods, limits and funding Outcomes: Bacterial species abundance by 16S sequencing; butyrate-producing bacteria Limitations: Fermentation in a dish, not in people. The authors say human trials are needed. Two authors are linked to the Chopra Foundation (disclosed). Funding and conflicts: D.C. and P.J.M. have disclosed Chopra Foundation roles. Read: abstract
Rahman 2017 Drug-Herb Interactions in the Elderly Patient with IBD: a Growing Concern. Curr Treat Options Gastroenterol · PMID 28918484 · DOI	Narrative review	Older people with inflammatory bowel disease (Crohn disease, ulcerative colitis) (review of herbs and drug interactions)	About 25 herbs and supplements including Ulmus rubra (slippery elm bark) bark	The abstract lists Ulmus rubra among the herbs reviewed for evidence in IBD and for interactions with IBD drugs. The abstract does not give the slippery elm findings. None in abstract Methods, limits and funding Outcomes: Herb background, evidence in IBD and possible interactions with IBD medicines Limitations: Only the abstract was read, so the slippery elm section of the review was not seen. Funding and conflicts: No conflict statement in the abstract. Read: abstract
Ried 2020 Herbal formula improves upper and lower gastrointestinal symptoms and gut health in Australian adults with digestive disorders. Nutr Res · PMID 32151878 · DOI	Pre post study	43 Australian adults with digestive disorders (upper and lower gut symptoms); 43 completed	Nutrition Care Gut Relief Formula: curcumin, Aloe vera, slippery elm, guar gum, pectin, peppermint oil, glutamine (amounts of each not stated in the abstract) bark (one of seven ingredients) 5 g/day then 10 g/day for 4 weeks each (after a control phase) 16 weeks in total · vs Own control phase (no placebo group)	Authors report symptom frequency and severity improved by 60 to 80%; most people with normal stool had normal permeability at the end; Lactobacillus, Clostridium and Faecalibacterium prausnitzii rose; almost half of those with upper gut symptoms who took proton pump inhibitors no longer needed them. Symptoms improved 60-80% (authors); about half of PPI users stopped (authors) Methods, limits and funding Outcomes: Validated symptom questionnaires (Leeds Dyspepsia, Bristol Stool Chart, Birmingham IBS), intestinal permeability (lactulose to mannitol ratio), gut microbiota, proton pump inhibitor use Limitations: Seven-ingredient formula, so slippery elm cannot be credited. No placebo group, no blinding, small. Self-reported symptoms. Stopping medicines is a result of the study design and should not be copied at home. Funding and conflicts: Not stated in the abstract. Authors are from an integrative medicine institute and the formula carries a company brand name, so an industry link is possible. Read: abstract
Shahrajabian 2024 Iranian Traditional Medicine (ITM) and Natural Remedies for Treatment of the Common Cold and Flu. Rev Recent Clin Trials · PMID 38047364 · DOI	Narrative review	Traditional Iranian medicine for colds and flu (review)	Many plants; slippery elm listed as expectorant and as immune-stimulating bark	The abstract lists slippery elm among expectorant and immunostimulant plants for colds and flu. It reports no trial result for slippery elm. None Methods, limits and funding Outcomes: Literature on herbs for colds and flu Limitations: A literature overview listing traditional uses. Only the abstract was read. It is not evidence that slippery elm works. Funding and conflicts: Not stated in the abstract. Read: abstract
Tinsley 2019 A Purported Detoxification Supplement Does Not Improve Body Composition, Waist Circumference, Blood Markers, or Gastrointestinal Symptoms in Healthy Adult Females. J Diet Suppl · PMID 29958034 · DOI	Controlled trial	22 Healthy young women (22 completed)	Multi-ingredient "detox" supplement: papaya leaf, cascara sagrada bark, slippery elm bark, peppermint leaf, red raspberry leaf, fenugreek seed, ginger root and senna leaf (proprietary blend, 1,350 mg per serving) bark (one of eight ingredients) 1,350 mg per serving, daily 4 weeks · vs Placebo	No beneficial or harmful effects on body composition, waist, stomach and bowel symptoms or blood markers. The authors call the product apparently safe in healthy young women but not beneficial for those outcomes. No difference versus placebo Methods, limits and funding Outcomes: Body composition, waist circumference, gastrointestinal symptoms, blood safety markers Limitations: Tiny trial in healthy women, not people with symptoms. A blend including two laxatives (cascara, senna) and seven other herbs; slippery elm cannot be separated out. Funding and conflicts: Not stated in the abstract. Read: abstract
WILLIAMS 1954 Two cases of slippery elm bladder calculus in pregnancy. J Obstet Gynaecol Br Emp · PMID 13192523 · DOI	Case report	2 Two women, pregnant, with a bladder stone formed around slippery elm (1954 case report)	Slippery elm (form not known; abstract not available) bark (presumed) Unknown Unknown	Only the title was read: it describes two cases of a bladder stone made of slippery elm during pregnancy. No abstract is available in PubMed, so how the elm reached the bladder is not known from what we read. None Methods, limits and funding Outcomes: Bladder stone (calculus) in pregnancy Limitations: Only the title and index record were seen; do not read more into it than the title says. Funding and conflicts: Not stated. Read: summary-only
Wijesundara 2019 Bactericidal and Anti-Biofilm Activity of Ethanol Extracts Derived from Selected Medicinal Plants against Streptococcus pyogenes. Molecules · PMID 30909644 · DOI	Laboratory research in-vitro	Streptococcus pyogenes (the bacterium behind strep throat) grown in the laboratory	Ethanol extracts of 14 plants, including slippery elm inner bark inner bark · vs Other plant extracts	Licorice root, purple coneflower flower and stem, sage leaf and slippery elm inner bark extracts were among the most effective: minimum inhibitory concentration 62.5 microgram/mL and minimum bactericidal concentration 125 microgram/mL. The authors singled out sage leaf and purple coneflower flower as the most promising candidates. MIC 62.5 microgram/mL; MBC 125 microgram/mL Methods, limits and funding Outcomes: Minimum inhibitory and bactericidal concentrations; biofilm inhibition Limitations: Alcohol extracts in a dish. A tea, lozenge or powder swallowed by a person is not the same. No human data. Funding and conflicts: The authors declare no conflict of interest. Read: abstract
Zick 2006 Trial of Essiac to ascertain its effect in women with breast cancer (TEA-BC). J Altern Complement Med · PMID 17212569 · DOI	Cohort retrospective	510 Women randomly chosen from the Ontario cancer registry with breast cancer diagnosed in 2003	Essiac, a blend of burdock root, Indian rhubarb, sheep sorrel and slippery elm inner bark (Resperin Canada) inner bark (one of four herbs) Total daily dose 43.6 +/- 30.8 mL (label directions) · vs Women who never used Essiac	Essiac did not improve quality of life or mood. Users did slightly worse on two subscales (physical well-being, relationship with doctor), possibly because users had more advanced disease. Only 2 women reported minor adverse events. No benefit on quality of life Methods, limits and funding Outcomes: Health-related quality of life (FACT-B), depression, anxiety, fatigue, adverse events Limitations: Observational, so users and non-users differ. A four-herb blend. Self-reported. Funding and conflicts: Not stated in the abstract. Read: abstract
s-ecfr-21cfr-341-310-201 eCFR Title 21: Part 341 (cold, cough, allergy OTC drugs), section 310.545 and section 201.319 (2025-10-01 text) · Source	Regulation n/a			Methods, limits and funding Read: full-text
s-gbif-ulmus-rubra GBIF Backbone: Ulmus rubra Muhl. (usageKey 5361867) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-mskcc-slippery-elm Memorial Sloan Kettering: Slippery Elm (Ulmus rubra) · Source	Consumer reference n/a			Methods, limits and funding Read: full-text
s-ncbi-taxonomy-ulmus-rubra NCBI Taxonomy: Ulmus rubra (taxid 102693) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-rxlist-slippery-elm RxList: Slippery Elm (medical editor J. Cunha; cites Medscape) · Source	Consumer reference n/a			Methods, limits and funding Read: full-text
s-traditional-medicinals-throat-coat Traditional Medicinals: Throat Coat product page (current label) · Source	Manufacturer page n/a			Methods, limits and funding Read: full-text
s-ups-slippery-elm-burkhart United Plant Savers: Slippery Elm in the Herbal Marketplace - Past, Present & Future (E. Burkhart) · Source	Conservation report n/a			Methods, limits and funding Read: full-text
s-webmd-slippery-elm WebMD: Slippery Elm - Uses, Side Effects, and More (reviewed 29 Sep 2025) · Source	Consumer reference n/a			Methods, limits and funding Read: full-text
s-wikipedia-ulmus-rubra Wikipedia: Ulmus rubra (NOT verified against primary sources) · Source	Encyclopedia n/a			Methods, limits and funding Read: full-text

What we do not know yet

What the evidence supports: a short-term sore throat benefit from one multi-herb tea (low certainty).
What is uncertain: whether slippery elm itself does anything for the throat, stomach, bowel or skin.
No trial of slippery elm alone for any condition was found.
No study measured whether it changes the absorption of other medicines.
No data on pregnancy or breastfeeding beyond cautions from consumer references without trials.
No testing of products for adulteration or other elm species.

How new research is added

New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it is added.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 13

▼

Throat pain on swallowing

Lowered in trials

A rating of how much it hurts to swallow, scored repeatedly after a drink.

Low certainty

Results and what it means

Why it was measured

The main outcome of the Throat Coat trial.

Statistical vs. clinical meaning

Statistically significant over 30 minutes after the first dose; how long the relief lasted beyond that is not shown.

Safety implication

None specific.

Study	Result	People	Product
⁴	SPID -43.8 (SEM 11.9) with Throat Coat versus -16.5 (SEM 13.9) with placebo, p = 0.012; TOTPAR 53.6 versus 32.4, p = 0.031	Adults with acute pharyngitis, n=60	Multi-herb demulcent tea containing slippery elm (label order, current product)

⁴

▼

Bacterial growth stopped in a dish (MIC and MBC)

Lowered in trials

The smallest amount of an extract that stops (MIC) or kills (MBC) bacteria in a laboratory dish.

Very low certainty

Results and what it means

Why it was measured

A first screen for activity against the bacterium behind strep throat.

Statistical vs. clinical meaning

A laboratory number only; not a human outcome.

Safety implication

None.

Study	Result	People	Product
²¹	MIC 62.5 microgram/mL and MBC 125 microgram/mL for the most effective extracts, including slippery elm inner bark	Streptococcus pyogenes in the laboratory	Ethanol extract of slippery elm inner bark

²¹

▼

Digestive symptom questionnaire scores

Lowered in trials

Questionnaires that score indigestion, heartburn, nausea and bowel symptoms.

Very low certainty

Results and what it means

Why it was measured

The main outcome of the formula study.

Statistical vs. clinical meaning

Self-reported, no placebo group.

Safety implication

Do not stop acid-reducing medicines without your doctor.

Study	Result	People	Product
¹⁷	Authors report 60-80% improvement in frequency and severity of upper and lower gut symptoms (numbers per item not in abstract)	43 adults with digestive disorders	Seven-ingredient formula including slippery elm, 5 then 10 g/day

¹⁷

▼

Use of proton pump inhibitor medicines

Lowered in trials

Whether people still took acid-reducing medicines at the end of the study.

Very low certainty

Results and what it means

Why it was measured

A practical sign of heartburn control.

Statistical vs. clinical meaning

Uncontrolled; depends on how the study guided medicine changes.

Safety implication

Medicine changes only with a doctor.

Study	Result	People	Product
¹⁷	Almost half of participants with upper gut symptoms who were on proton pump inhibitors no longer needed them by the end (authors)	Adults with upper gut symptoms	Seven-ingredient formula including slippery elm

¹⁷

▼

Free radical scavenging in the laboratory

Lowered in trials

How well an extract neutralises reactive oxygen molecules in test tubes.

Very low certainty

Results and what it means

Why it was measured

Screening for antioxidant activity.

Statistical vs. clinical meaning

Lab only.

Safety implication

None.

Study	Result	People	Product
¹⁰	Superoxide scavenged dose-dependently; peroxyl scavenged; oxygen radical release from inflamed colon biopsies reduced (no numbers in abstract)	Cell-free systems and colitis biopsies	Slippery elm extract
⁶	Slippery elm ranked fifth of the eight herbs listed for peroxynitrite scavenging	28 herb extracts	Slippery elm extract

^{10 6}

▲

Bowel movement frequency

Raised in trials

How many times a week or day a person has a bowel movement.

Very low certainty

Results and what it means

Why it was measured

A basic outcome for constipation-type IBS.

Statistical vs. clinical meaning

Open-label with no control group.

Safety implication

None.

Study	Result	People	Product
⁹	C-IBS group: +20% (p = 0.016); DA-IBS group: small but significant rise (p = 0.027)	31 adults with IBS	Two herbal mixtures containing slippery elm bark

⁹

↕

Stool consistency

Mixed results in trials

How hard or soft stool is, often rated on a chart.

Very low certainty

Results and what it means

Why it was measured

Tracks constipation or diarrhoea.

Statistical vs. clinical meaning

Lactulose and oat bran in the constipation blend can soften stool alone.

Safety implication

None.

Study	Result	People	Product
⁹	Improved in the constipation group (p < 0.0001); the diarrhoea/mixed group did not improve bowel habit	31 adults with IBS	Two herbal mixtures containing slippery elm bark

⁹

▼

Abdominal pain, bloating and straining

Lowered in trials

Patient-rated gut discomfort scores.

Very low certainty

Results and what it means

Why it was measured

Core IBS symptoms.

Statistical vs. clinical meaning

No placebo group, so improvement could be natural fluctuation or expectation.

Safety implication

None.

Study	Result	People	Product
⁹	C-IBS: straining p < 0.0001, abdominal pain p = 0.032, bloating p = 0.034; DA-IBS: straining p = 0.004, pain p = 0.006, bloating p < 0.0001	31 adults with IBS	Two herbal mixtures containing slippery elm bark

⁹

▼

Intestinal permeability (lactulose-to-mannitol ratio)

Lowered in trials

A urine test of how much of two sugars passes through the gut lining.

Very low certainty

Results and what it means

Why it was measured

Used as a rough measure of "leaky gut".

Statistical vs. clinical meaning

A test result; the link to how people feel is unclear.

Safety implication

None.

Study	Result	People	Product
¹⁷	Most participants had normal ratios by the end (all with normal stool, 90% with hard stool, 66% with soft stool)	43 adults with digestive disorders	Seven-ingredient formula including slippery elm
⁵	Average ratio 0.066 to 0.026 over six months	5 adults with psoriasis	Whole-diet programme with slippery elm bark water

^{17 5}

▲

Gut bacteria mix

Raised in trials

Which bacteria are present and in what amounts.

Very low certainty

Results and what it means

Why it was measured

Gut bacteria are linked to digestion and inflammation.

Statistical vs. clinical meaning

More of a bacterium is not the same as better health.

Safety implication

None.

Study	Result	People	Product
¹⁵	Butyrate-producing bacteria rose significantly in stool cultures with Ulmus rubra (laboratory)	Human stool cultures	Ulmus rubra
¹⁷	Lactobacillus, Clostridium and Faecalibacterium prausnitzii rose (authors)	43 adults	Seven-ingredient formula

^{15 17}

●

Body composition and waist circumference

No clear change in trials

Fat and lean mass, and waist measurement.

Low certainty

Results and what it means

Why it was measured

Detox blends claim to change these.

Statistical vs. clinical meaning

Null result.

Safety implication

Blood safety markers unchanged.

Study	Result	People	Product
¹⁹	No beneficial or harmful effect versus placebo	22 healthy young women	Eight-herb blend including slippery elm, 4 weeks

¹⁹

▼

Psoriasis severity scores (PASI, PSS)

Lowered in trials

Doctor-rated skin scores.

Very low certainty

Results and what it means

Why it was measured

Outcome of the psoriasis case series.

Statistical vs. clinical meaning

Five people, no control.

Safety implication

None.

Study	Result	People	Product
⁵	PASI 18.2 to 8.7; PSS 14.6 to 5.4 (averages)	5 adults	Whole-diet programme with slippery elm bark water

⁵

●

Health-related quality of life in breast cancer (FACT-B)

No clear change in trials

A questionnaire scoring physical, emotional and social well-being.

Low certainty

Results and what it means

Why it was measured

Main outcome of the Essiac cohort.

Statistical vs. clinical meaning

Observational; users had more advanced disease.

Safety implication

Only 2 women reported minor adverse events.

Study	Result	People	Product
²²	No significant improvement; users did worse on physical well-being and relationship-with-doctor subscales	510 women with breast cancer	Essiac (includes slippery elm), about 44 mL/day

²²

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 7

Mucilage can get in the way of other medicines. Slippery elm is rich in mucilage, a gel-forming fibre. WebMD says it "may affect the absorption of some medicines" and that how it interacts with medicines is not fully understood. This is a theory based on how gels and fibres behave in the gut. We found no study that measured the blood levels of any medicine taken with slippery elm. Because the effect is unmeasured, ask a pharmacist how far apart to take your medicines and slippery elm. Pharmacological theory ³⁰
Allergy is possible, and one case report links it to a bowel reaction. WebMD says serious allergic reactions are possible (hives, facial swelling, trouble breathing). RxList lists allergic reaction and contact dermatitis. A 2021 case report from Portugal describes a woman whose rare eosinophilic colitis (an allergy-like bowel inflammation) was potentially triggered by an Ulmus rubra-rich product. One case shows something happened, not how often. Case report ^{30 27 3}
Pregnancy: avoid, because safety is unknown and an old warning exists. WebMD says it is not known how slippery elm might affect pregnancy. RxList states that slippery elm is an abortifacient that may cause miscarriage (whole bark) and says to avoid it in pregnancy and breastfeeding, but gives no source or study in the text we read. The warning appears to come from old folk use of the bark. We did not find a trial or a case series showing miscarriage from slippery elm taken by mouth. Until better information exists, pregnant and breastfeeding women should avoid it or ask their doctor. Traditional use ^{30 27}
Liver: no sign of harm in LiverTox. The US government LiverTox entry says slippery elm preparations are generally recognized as safe and that there is no evidence they cause raised liver enzymes or clinically apparent liver injury. Authoritative guidance ¹²
Blends carry the risks of their other herbs. Most research and most products are blends. Throat Coat lists licorice root, marshmallow, wild cherry bark, fennel, cinnamon and orange peel besides slippery elm. A "detox" blend that was tested contained cascara and senna, which are stimulant laxatives. Read the whole label, not only the slippery elm line. Authoritative guidance ^{28 19}
The tree is under pressure, so choose carefully sourced products. United Plant Savers puts slippery elm on its At-Risk List because the trade depends on wild-harvested bark and the tree is hit by Dutch elm disease and elm yellows. Globally the species is not endangered (Wikipedia, citing IUCN Least Concern; NOT verified against IUCN). Taking bark can kill a tree if it is stripped all around. Authoritative guidance ^{29 31}
Do not skip care for a serious problem. A sore throat with fever and no cough may be strep throat, which can need antibiotics. Long-lasting bowel change, blood in stool, weight loss, or chest pain must be checked. The only throat trial lasted a few days and showed short relief. Memorial Sloan Kettering says there is no evidence slippery elm treats infections, cancer or other serious conditions. Authoritative guidance ^{4 25}

Side effects 5

Effect	How often	Severity and recovery	Evidence
Allergic reaction (hives, swelling, breathing trouble) WebMD says serious allergic reactions may happen. No rate is given.	Not established	can be serious Stop use and get help; outcome not described in sources	Authoritative guidance ^{30 27}
Contact dermatitis (skin rash) Listed by RxList; no source cited for the frequency.	Not established	mild to moderate (not graded) Not described	Authoritative guidance ²⁷
Eosinophilic colitis (rare allergy-type bowel inflammation) The authors say the product potentially triggered it; causation not proven.	One case report	moderate The abstract says this type responds well to corticosteroids; whether the patient recovered after stopping the product is not in the abstract	Case report ³
Minor side effects in blend studies All are blends or uncontrolled; counts from abstracts, not rates for slippery elm alone.	2 of the Essiac users reported minor adverse events (cohort of 510 women); both IBS formulas were described as well-tolerated (31 people); no harm in blood markers in 22 healthy women	mild Not described	Cohort study ^{22 9 19}
Bladder stone or foreign body after surgical or insertion use (historical) Titles describe slippery elm found in or forming a stone in the bladder; the 1837 title describes surgical use of the bark. Not oral use as sold today, and not read beyond titles.	Case reports from 1932 and 1954	unknown Unknown (only titles seen)	Case report ^{2 20 14}

Liver

LiverTox (US National Institutes of Health) says slippery elm preparations are generally recognized as safe and that there is no evidence they raise liver enzymes or cause clinically apparent liver injury. None of the studies we read reported liver harm, but their abstracts do not report liver tests except blood safety markers unchanged in the 22-woman blend trial. ^{12 19}

How often. No frequency given. LiverTox found no evidence of injury. Not finding reports is not proof of safety.

Monitoring. No monitoring advice given. Products that mix in licorice or other herbs have their own liver and blood-pressure notes.

This is a safety connection. It is not evidence that Slippery Elm supports liver health.

Medicines and supplements 4

With	Why it matters	Importance	Evidence	What to do
Any medicine taken by mouth at the same time (general) prescription	Mucilage forms a gel and could slow or reduce absorption of other swallowed substances. This is a theory about how fibre behaves; no blood-level study of slippery elm was found.	WebMD says it may affect absorption of some medicines and that the interactions are not fully understood. RxList says no known severe interactions, with no source shown. These two sources disagree. One web search summary reported a database advising to space doses by one to two hours; we could not read that database, so we do not give a number as fact.	Pharmacological theory Not enough evidence ^{30 27}	Ask your pharmacist how long to leave between slippery elm and each medicine. Do not stop a medicine on your own.
Medicines where small changes in the amount absorbed matter (for example thyroid hormone, blood thinners, seizure medicines, heart rhythm medicines, contraception) prescription	Same theory as above. The examples are our reasoning from the mucilage idea; none was tested with slippery elm.	No studies and no case reports with slippery elm were found for these medicines.	Pharmacological theory Not enough evidence ³⁰	Tell your pharmacist and doctor before starting; they may suggest spacing or checking blood tests.
Inflammatory bowel disease medicines taken by mouth prescription	A review of herb-drug interactions in older people with IBD covers Ulmus rubra; the abstract does not give the details.	Not seen (abstract only). The mucilage theory applies.	Authoritative guidance Not enough evidence ¹⁶	Talk to your gastroenterologist before adding it.
Other laxatives or stimulant herbs in a blend (cascara, senna, rhubarb) herb	Some blends that contain slippery elm also contain stimulant laxatives, so their effects add up.	The detox trial blend contained cascara and senna; Essiac contains Indian rhubarb. Interaction with slippery elm itself not studied.	Authoritative guidance Not enough evidence ^{19 22}	Check the label for laxative plants.

Who should check first 4

Situation	Advice	Evidence
Allergy to slippery elm or any ingredient in the product	Do not use. WebMD and RxList list this.	Authoritative guidance ^{30 27}
Pregnancy and breastfeeding	Avoid unless your doctor agrees. Safety is unknown; RxList calls whole bark an abortifacient (source not shown).	Traditional use ^{30 27}
A past allergy-type bowel inflammation (eosinophilic colitis)	Avoid unless your gastroenterologist agrees; this rests on one case report.	Case report ³
Taking time-critical swallowed medicines	Ask a pharmacist about timing before use.	Pharmacological theory ³⁰

Overdose, product quality and regulators

Summary. No toxic dose of slippery elm bark is documented in the sources we read. LiverTox says preparations are generally recognized as safe.

Animal. No animal toxicity study was found in this search.

Human doses studied. Only blends were studied: a gut formula at 5 then 10 g a day for 4 weeks each, a 1,350 mg-per-serving detox blend for 4 weeks, and Essiac at about 44 mL a day. Slippery elm amounts inside them are not in the abstracts.

High dose or long term signals. Not found. Long-term use of slippery elm alone has not been studied.

Overdose response. Not found. RxList advises calling a Poison Control Center in case of overdose (general text).

Genotoxicity. Not found.

Toxic plant parts. No toxic part of the bark was identified in the sources read. Leaves are sometimes made into tea per Wikipedia (NOT verified); inner bark is the studied part.

We found no published testing of slippery elm products for adulteration, heavy metals, or species mix-ups, so a product-quality picture cannot be given. Dutch elm disease is a disease of the tree, not a proven contaminant of bark products.

Adulteration and other elm species. No analysis of slippery elm powders for substitution with other elm species or fillers was found. The United Plant Savers article does not discuss adulteration. GBIF lists Ulmus fulva only as a synonym of U. rubra, so labels using the old name are still the same species. ^{29 24}

Dutch elm disease and elm yellows. The trees are widely killed by Dutch elm disease and elm yellows and seldom reach commercial size. The same article suggests harvesting dying trees, so some bark may come from diseased trees. No source we read says such bark is unsafe to swallow. ²⁹

Wild harvest and over-harvesting. AHPA surveys cited by United Plant Savers put wild-harvested dried bark at 78,000 to 353,000 pounds a year (1999-2010); cultivated bark is a small share. Reports say about a dozen trees yield fifty pounds of fresh bark. Stripping all around a trunk kills it. ²⁹

Blends. The tested products were blends; hidden extra ingredients (laxative herbs) matter more than contamination of the bark. ^{19 28}

Body	Action	Date
US Food and Drug Administration (United States)	WebMD says the FDA has not reviewed slippery elm for safety and effectiveness. In the eCFR text of 21 CFR Part 341 (cold, cough and allergy drugs), section 310.545 and 201.319 (2025-10-01 version), the words "slippery elm" and "elm" do not appear. Part 341 refers to a "generally recognized as safe and effective single oral demulcent" but names none in the text we read. Websites claim FDA lists elm bark as a lozenge demulcent; we could not find that in the regulation. source	2025-10-01
US National Institutes of Health, LiverTox (United States)	Entry on slippery elm: generally recognized as safe; no evidence of liver injury. source	2024-01-05
Memorial Sloan Kettering Cancer Center (United States)	Patient page: may relieve minor cough or sore throat; no evidence it treats infections, cancer or other serious conditions. source
United Plant Savers (United States)	Slippery elm on the At-Risk List. source

When to get medical help

Hives, swelling of the face or lips, or trouble breathing after taking it: stop and get emergency help.
Belly pain, bloating or swelling with diarrhoea that does not settle after a product containing slippery elm: see a doctor (rare case of eosinophilic colitis).
Sore throat with high fever, white patches, or trouble swallowing or breathing: see a doctor; do not rely on slippery elm.
Blood in stool, black stool, weight loss or heartburn with chest pain: see a doctor.
You are pregnant and took a large amount of bark or any bark inserted into the body: tell your doctor.
Taking a time-critical medicine (for example thyroid, seizure or heart rhythm medicine) and unsure about timing: ask your pharmacist.

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is slippery elm?

Slippery elm (Ulmus rubra, also called red elm; the older name Ulmus fulva is the same tree) is a North American tree. The inner bark is dried and powdered. Mixed with water it makes a slippery gel called mucilage, which is why it has long been used as a soothing remedy for sore throat and an upset stomach.

^{24 25 12}

Does slippery elm help a sore throat?

Possibly for a short time, but we cannot say that slippery elm itself does it. One trial of 60 adults found a multi-herb tea that contains slippery elm eased throat pain for about 30 minutes after the first drink more than a placebo tea did. No trial tested slippery elm alone. Certainty is low.

^{4 28}

Does slippery elm help a cough or a cold?

Not shown. It is traditionally used for coughs, but we found no human trial for cough or colds. Memorial Sloan Kettering says there is no evidence it treats infections.

^{18 25}

Can slippery elm help heartburn or acid reflux?

It is a popular home remedy, but there is no trial of slippery elm alone. A review of popular reflux remedies lists it among herbs with a gap between stories and proof. A small uncontrolled study of a seven-ingredient blend reported fewer symptoms, but a blend cannot show what slippery elm does.

^{1 17}

Does it work for irritable bowel syndrome or constipation?

Unclear. In a small open study, a blend of slippery elm, lactulose, oat bran and licorice root was followed by more frequent, softer stools in 10 people with constipation-type IBS. The other ingredients can ease constipation by themselves, and there was no placebo group.

⁹

Is slippery elm useful for Crohn disease or ulcerative colitis?

There is no trial in people. In a laboratory, extract calmed oxygen radicals in colitis tissue. That is a reason to study it, not proof that it helps. Do not use it in place of your IBD medicines.

^{10 16}

Does slippery elm treat cancer?

No. Memorial Sloan Kettering says there is no evidence it treats cancer. Slippery elm is one of the four herbs in Essiac tea; a study of 510 women with breast cancer found Essiac users did not have better quality of life.

^{22 25}

Can slippery elm affect my other medicines?

Possibly. The gel-like mucilage could slow or reduce how much of a swallowed medicine your body absorbs. WebMD says it may affect absorption of some medicines, but this has not been measured in a study, and another reference says there are no known severe interactions. Ask a pharmacist about timing, especially for thyroid, blood-thinning, seizure or heart medicines.

^{30 27}

Is slippery elm safe to take?

The US LiverTox entry says slippery elm preparations are generally recognized as safe and found no evidence of liver injury. Allergic reactions are possible, and one case report links an Ulmus rubra-rich product to a rare allergy-type bowel inflammation. Long-term safety has not been studied.

^{12 30 3}

Is slippery elm safe in pregnancy or while breastfeeding?

It is best avoided. WebMD says its effects in pregnancy and breast milk are not known. RxList states that whole bark is an abortifacient that may cause miscarriage, but shows no study for that claim, and we found no trial or case series of it with slippery elm taken by mouth. Ask your doctor.

^{30 27}

Is slippery elm an endangered tree?

Not globally (Least Concern on the IUCN list according to Wikipedia, which we have not verified), but United Plant Savers lists it as At-Risk because most bark is taken from wild trees and Dutch elm disease and elm yellows are killing the trees. Stripping bark all the way around a trunk kills it.

^{29 31}

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We searched PubMed, read the abstracts of every study cited, read the US government LiverTox summary, the Memorial Sloan Kettering and WebMD and RxList pages, the United Plant Savers article and the current text of the main FDA cough and cold rule.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. If one is added later it will be labelled as such.

Sources 31

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Ahuja A, Ahuja NK. Popular Remedies for Esophageal Symptoms: a Critical Appraisal.. Curr Gastroenterol Rep. 2019. PMID 31289950. DOI 10.1007/s11894-019-0707-4. (abstract)
Ainsworth-Davis JC. A Piece of Slippery Elm Removed from the Bladder.. Proc R Soc Med. 1932. PMID 19988576. DOI 10.1177/003591573202500478. (summary-only)
Amado C, Silva Leal M, Neto P et al.. Subserous Type of Eosinophilic Colitis: A Rare Disease.. Eur J Case Rep Intern Med. 2021. PMID 34377693. DOI 10.12890/2021_002671. (abstract)
Brinckmann J, Sigwart H, van Houten Taylor L. Safety and efficacy of a traditional herbal medicine (Throat Coat) in symptomatic temporary relief of pain in patients with acute pharyngitis: a multicenter, prospective, randomized, double-blinded, placebo-controlled study.. J Altern Complement Med. 2003. PMID 12804082. DOI 10.1089/10755530360623400. (abstract)
Brown AC, Hairfield M, Richards DG et al.. Medical nutrition therapy as a potential complementary treatment for psoriasis--five case reports.. Altern Med Rev. 2004. PMID 15387720. (abstract)
Choi HR, Choi JS, Han YN et al.. Peroxynitrite scavenging activity of herb extracts.. Phytother Res. 2002. PMID 12112294. DOI 10.1002/ptr.904. (abstract)
GILL RE, HIRST EL, JONES JK. Constitution of the mucilage from the bark of Ulmus fulva (slippery elm mucilage); the sugars formed in the hydrolysis of the methylated mucilage.. J Chem Soc. 1946. PMID 20282480. DOI 10.1039/jr9460001025. (summary-only)
HOUGH L, JONES JK, HIRST EL. Chemical constitution of slippery elm mucilage; isolation of 3-methyl d-galactose from the hydrolysis products.. Nature. 1950. PMID 15400433. DOI 10.1038/165034a0. (summary-only)
Hawrelak JA, Myers SP. Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study.. J Altern Complement Med. 2010. PMID 20954962. DOI 10.1089/acm.2009.0090. (abstract)
Langmead L, Dawson C, Hawkins C et al.. Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study.. Aliment Pharmacol Ther. 2002. PMID 11860402. DOI 10.1046/j.1365-2036.2002.01157.x. (abstract)
Leonard SS, Keil D, Mehlman T et al.. Essiac tea: scavenging of reactive oxygen species and effects on DNA damage.. J Ethnopharmacol. 2006. PMID 16226859. DOI 10.1016/j.jep.2005.09.013. (abstract)
LiverTox (NIDDK). Slippery Elm.. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury (NIDDK), updated 5 Jan 2024. 2024. PMID 38289993. (abstract)
Manville RW, Redford KE, van der Horst J et al.. KCNQ5 activation by tannins mediates vasorelaxant effects of barks used in Native American botanical medicine.. FASEB J. 2022. PMID 35997997. DOI 10.1096/fj.202200724R. (abstract)
McDowell WA. Elm Bark in Surgery: An Account of the Use of the Bark of the Slippery Elm Tree (Ulmus Fulva), for Bougies, Tents, Catheters, and Similar Purposes in Surgery.. West J Med Phys Sci. 1837. PMID 38080966. (summary-only)
Peterson CT, Sharma V, Uchitel S et al.. Prebiotic Potential of Herbal Medicines Used in Digestive Health and Disease.. J Altern Complement Med. 2018. PMID 29565634. DOI 10.1089/acm.2017.0422. (abstract)
Rahman H, Kim M, Leung G et al.. Drug-Herb Interactions in the Elderly Patient with IBD: a Growing Concern.. Curr Treat Options Gastroenterol. 2017. PMID 28918484. DOI 10.1007/s11938-017-0154-y. (abstract)
Ried K, Travica N, Dorairaj R et al.. Herbal formula improves upper and lower gastrointestinal symptoms and gut health in Australian adults with digestive disorders.. Nutr Res. 2020. PMID 32151878. DOI 10.1016/j.nutres.2020.02.008. (abstract)
Shahrajabian MH, Sun W. Iranian Traditional Medicine (ITM) and Natural Remedies for Treatment of the Common Cold and Flu.. Rev Recent Clin Trials. 2024. PMID 38047364. DOI 10.2174/0115748871275500231127065053. (abstract)
Tinsley G, Urbina S, Santos E et al.. A Purported Detoxification Supplement Does Not Improve Body Composition, Waist Circumference, Blood Markers, or Gastrointestinal Symptoms in Healthy Adult Females.. J Diet Suppl. 2019. PMID 29958034. DOI 10.1080/19390211.2018.1472713. (abstract)
WILLIAMS B. Two cases of slippery elm bladder calculus in pregnancy.. J Obstet Gynaecol Br Emp. 1954. PMID 13192523. DOI 10.1111/j.1471-0528.1954.tb07516.x. (summary-only)
Wijesundara NM, Rupasinghe HPV. Bactericidal and Anti-Biofilm Activity of Ethanol Extracts Derived from Selected Medicinal Plants against Streptococcus pyogenes.. Molecules. 2019. PMID 30909644. DOI 10.3390/molecules24061165. (abstract)
Zick SM, Sen A, Feng Y et al.. Trial of Essiac to ascertain its effect in women with breast cancer (TEA-BC).. J Altern Complement Med. 2006. PMID 17212569. DOI 10.1089/acm.2006.12.971. (abstract)
. eCFR Title 21: Part 341 (cold, cough, allergy OTC drugs), section 310.545 and section 201.319 (2025-10-01 text). . . (full-text)
. GBIF Backbone: Ulmus rubra Muhl. (usageKey 5361867). . . (full-text)
. Memorial Sloan Kettering: Slippery Elm (Ulmus rubra). . . (full-text)
. NCBI Taxonomy: Ulmus rubra (taxid 102693). . . (full-text)
. RxList: Slippery Elm (medical editor J. Cunha; cites Medscape). . . (full-text)
. Traditional Medicinals: Throat Coat product page (current label). . . (full-text)
. United Plant Savers: Slippery Elm in the Herbal Marketplace - Past, Present & Future (E. Burkhart). . . (full-text)
. WebMD: Slippery Elm - Uses, Side Effects, and More (reviewed 29 Sep 2025). . . (full-text)
. Wikipedia: Ulmus rubra (NOT verified against primary sources). . . (full-text)

Where to buy

Check the label first. Whatever you buy, look for these:

The plant part and the extract type or ratio on the label
A standardized amount of the active compounds, where relevant
A third-party testing mark (USP, NSF or ConsumerLab)
Interactions: ask a pharmacist if you take medicines, are pregnant or have a medical condition

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.