Herbs & Botanicals · Herbs · South African mood plant with very little human research and important antidepressant cautions

Kanna (Sceletium tortuosum)

Q: What is kanna?

Kanna is a succulent plant from South Africa, also called Sceletium or kougoed. Its dried or fermented leaves and stems were chewed, smoked or made into tea or tincture for mood, relaxation and pain. Today it is sold as powders, capsules, vapes and gummies. It is a psychoactive plant, not a proven treatment.

Q: Does kanna work for anxiety or depression?

Not shown. Two tiny studies of 20 healthy volunteers gave mixed results on laboratory anxiety, and no trial has tested kanna in people with depression or an anxiety disorder. A 2026 review calls the evidence mixed. Do not replace prescribed treatment with it.

Q: Can I take kanna with an SSRI or other antidepressant?

Ask a doctor or pharmacist first. Kanna blocks the serotonin transporter in lab tests, like SSRIs. A drug reference lists SSRIs, SNRIs, tricyclics, MAOIs, triptans, antipsychotics and St. John's wort as medicines to discuss first. No study or case report tested the combination, so the risk of too much serotonin is a reasoned concern rather than a documented event.

Q: Is kanna safe with MAOIs?

A drug reference says to discuss any MAOI taken within the past two weeks. There is no human data on the combination, so the safe course is to avoid it unless a doctor agrees.

Q: What does PDE4 inhibition mean for medicines?

The extract and one of its alkaloids block the enzyme PDE4 in lab tests. Some medicines for lung and skin conditions also block PDE4. No source tested kanna with them, so this is only a possible overlap; ask a pharmacist if you take one.

Q: What are the side effects?

Headache and upset stomach are listed by a drug reference. In a 3-month trial of 37 healthy adults headache and stomach pain were reported, but more often in the placebo groups. A military guidance page lists fatigue, drowsiness and trouble concentrating, and serious allergic reactions are possible.

Q: Is kanna safe in pregnancy or when breastfeeding?

Its effects are unknown. A drug reference states it is not known whether kanna affects pregnancy or passes into breast milk, so avoiding it is the cautious choice. Traditional use for babies is not evidence of safety.

Q: Can I drink alcohol or use sedatives or cannabis with kanna?

Not enough research exists to know. Kanna was traditionally used as a sedative and to cause intoxication, and a US military guidance page warns about combining it with cannabis or other psychoactive agents. Ask a doctor.

Q: Is kanna legal?

It depends on the country. The plant is native to South Africa, where a 2021 review says it is regulated as a food. The same review reports no legal products on the European market, no listing in Australia's ingredient lists, eleven licences in Canada (as of August 2020), and a ban on mesembrine in Russia. The US FDA has not approved it. Rules may have changed, so check local law.

Q: Are kanna products pure?

Not always. Ephedrine, a banned stimulant, was found in one commercial kanna sample, and hordenine content varied about 40-fold across six products. A military guidance page says products have been reported adulterated with hordenine and ephedrine. Independent lab testing is the only way to know what is inside.

Mesembryanthemum tortuosum L. (GBIF accepted name; widely sold and studied as Sceletium tortuosum (L.) N.E.Br.), family Aizoaceae · also called Kanna, kougoed, channa, Sceletium; Zembrin is a branded standardized extract

Kanna is a succulent plant from South Africa. Its dried or fermented leaves and stems were traditionally chewed, smoked or made into tea or tincture for mood, relaxation and pain, and to become intoxicated. Today it is sold as powders, capsules, vapes and gummies. Human research is limited to a few small studies of one branded extract in healthy people, and it is not shown to treat depression or anxiety. It acts on serotonin in lab tests, so it carries real cautions with antidepressants and other medicines.

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

About Kanna (Sceletium tortuosum)

Kanna is a South African succulent with a long history as a mood-altering plant. Modern research is small: a handful of trials of one branded extract in healthy people, and lab work showing it blocks the serotonin transporter and the enzyme PDE4. It has not been tested in people with depression or anxiety, and its biggest safety questions concern antidepressants, adulterated products and unclear legal status.

What it is

Kanna is the dried or fermented leaves and stems of Mesembryanthemum tortuosum, widely known by its former name Sceletium tortuosum. It belongs to the Aizoaceae (ice-plant) family and is native to dry regions of South Africa. GBIF and NCBI Taxonomy list Mesembryanthemum tortuosum as the accepted name and Sceletium tortuosum as a synonym.

Traditionally the plant was crushed, sealed in a bag and left in the sun for about eight days to ferment, then dried. It was chewed, smoked, or made into tea or tincture. Its main active compounds are the mesembrine-type alkaloids, mesembrine and mesembrenone.

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How it may work

In lab tests, kanna extract and mesembrine block the serotonin transporter, the same target as SSRI antidepressants, and the extract and mesembrenone block the enzyme PDE4. One brain-scan study in 16 healthy people found lower amygdala response to threat after a dose. Whether these actions explain any real-life effect is not shown.

Pharmacology is incomplete. No human study measured how the body absorbs or clears the alkaloids; rat and tissue work suggests they are absorbed quickly and broken down in several steps.

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Products that are not the same

Fermented traditional kanna, the Zembrin standardized extract, higher-mesembrine extracts, and powders, vapes and gummies are different products with different chemistry. Nearly all human trials used Zembrin, so their results cannot be applied to the others. Whether fermentation makes kanna stronger is unsettled.

A US military guidance page notes that all the human studies it reviewed were small, short and used Zembrin.

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Who ran the research

Most human trials and the safety study in rats include authors linked to HG&H Pharmaceuticals, the company behind Zembrin, or to its marketers. Two trials (Hoffman 2020 and parts of Reay 2020) were run by other groups but are also tiny. No large independent trial exists.

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At a glance

Traditional uses history, not proof

Chewed, smoked, or made into tea or tincture by the Khoikhoi and San peoples to lift mood, calm and relieve pain
Used as a sedative and to cause intoxication
Used for toothache, stomach cramps and colic, and by some healers to ease alcohol misuse

Studied for research

Anxiety under laboratory stress (Zembrin), very low certainty
Brain response to threatening faces (imaging), very low certainty
Thinking skills in healthy middle-aged adults (Zembrin), very low certainty
Reaction speed in trained young adults, very low certainty
Low mood and depression, insufficient evidence (never tested in patients)
Sleep and well-being, insufficient evidence
Pain, digestion and alcohol misuse (traditional only), insufficient evidence

Main compounds

Mesembrine and mesembrenone (mesembrine-type alkaloids)
Mesembrenol
Hordenine (naturally present; also reported as an added ingredient)

Common forms

Traditionally fermented dried plant (chewed, smoked, tea, tincture)
Standardized extract (Zembrin), used in nearly all human trials
Capsules, powders, vapes and gummies of unknown strength

Research links: Brendler 2021: kanna in modern regulatory systems (PubMed) · Terburg 2013: amygdala imaging trial (PubMed) · Nell 2013: 3-month safety trial (PubMed) · Operation Supplement Safety: Kanna · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Mesembryanthemum tortuosum L.
Naming authority: GBIF backbone (API, read 2026-10-25): Mesembryanthemum tortuosum L. (key 7750120) is ACCEPTED; Sceletium tortuosum (L.) N.E.Br. (key 3707372) is a SYNONYM pointing to it. NCBI Taxonomy (taxid 216016) also names the species Mesembryanthemum tortuosum, with Sceletium tortuosum as a synonym. Most research papers and products still use the name Sceletium tortuosum.
Synonyms: Sceletium tortuosum (L.) N.E.Br.
Common names: Kanna (English / Afrikaans); Kougoed (chewing stuff) (Afrikaans); Channa (English); Sceletium (Latin genus name used commercially)
Botanical family: Aizoaceae (ice-plant or fig-marigold family)
Classification: Plantae > Tracheophyta > Magnoliopsida > Caryophyllales > Aizoaceae > Mesembryanthemum > Mesembryanthemum tortuosum
Native range: South Africa. A 2021 review describes it as endemic to South Africa, occurring in dry karroid regions of the Western and Northern Cape.
Habitat: Dry karroid (calcareous soil) regions; a succulent forb.
What the plant looks like: Roots: Not verified.; Stems: Not verified.; Leaves: Succulent aerial parts (leaves and stems) are the part used.; Flowers: Not verified.; Fruit: Not verified.
Cultivation: Grown commercially for supplement ingredients in South Africa; details not verified.
Harvest and processing: Traditionally harvested October to January. The above-ground plant is crushed, sealed in a bag and left to macerate in the hot sun for about eight days, then dried in the sun; this fermented material is called kanna or kougoed. Some people simply crush and sun-dry the fresh plant. (2021 regulatory review quoting traditional practice.)
Look-alikes and adulterants: Name: Other Sceletium-group species; Note: The 2021 review says S. tortuosum is the only species used to any extent in traditional medicine and product development; look-alikes for identification were not verified in the sources read.
Sustainability and conservation: Not assessed in the sources read; access to the plant in South Africa is governed by biodiversity and benefit-sharing law (2021 review).

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Khoikhoi and San peoples, southern Africa	Fresh or fermented aerial parts chewed or smoked ('kauwgoed') for mood, relaxation, thirst and hunger, pain and toothache, and to become intoxicated; also made into tea or tincture. A 19th-century account described chewing leading to intoxication and use of a decoction or tincture as a sedative by farmers.	p33588735
Cape colonial period to the 20th century	Used as a sedative tea or tincture; stocked in Namaqualand stores until the 1990s. Healers in Namaqualand use it to treat alcohol misuse. Small amounts of juice or breast-milk preparations were given to babies for colic. Early researchers concluded the indigenous population used it more for recreation than as medicine.	p33588735
Modern supplement era (2000s onward)	A standardized extract (Zembrin) was developed and tested in small human trials from about 2009; kanna is also sold as powders, teas, vapes and gummies and is promoted as a 'party drug' by some sellers.	s-opss-kanna
European regulators	No EMA/HMPC assessment was found; the EMA site could not be searched automatically. A 2021 review states there were no legal sceletium products in the EU.	p33588735

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
Mesembrine PubChem 394162	mesembrine-type alkaloid	Aerial parts Under 20% of total alkaloids in Zembrin; higher in some other extracts.	Most potent serotonin-transporter blocker among the alkaloids tested (Ki 1.4 nM in a lab binding test). ^{6 11 16}	Laboratory research
Mesembrenone PubChem 216272	mesembrine-type alkaloid	Aerial parts With mesembrenol, at least 60% of total alkaloids in Zembrin.	Acts on both the serotonin transporter and PDE4 (IC50 below 1 uM) in lab tests. ^{6 11 16}	Laboratory research
Mesembrenol	mesembrine-type alkaloid	Aerial parts With mesembrenone, at least 60% of total alkaloids in Zembrin.	Tested with the other alkaloids in the lab; less potent details not extracted from the abstract. ^{6 11}	Laboratory research
Hordenine PubChem 68313	phenethylamine-type compound	Aerial parts 0.027 to 1.07 mg per gram in six commercial products.	Stimulant-like compound found naturally in kanna; also reported as an added ingredient in some products. Its effect in people from kanna is not established. ^{1 15 16}	Laboratory research
Other alkaloid classes (Sceletium A4, joubertiamine, tortuosamine)	alkaloids	Aerial parts 25 alkaloids in four classes have been identified; mesembrine class predominates.	Not detailed in the sources read. ¹⁴	Laboratory research

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Serotonin (5-HT) transporter	SLC6A4 (serotonin transporter)	Zembrin blocked the serotonin transporter in binding tests (IC50 4.3 ug/mL); mesembrine was the most potent alkaloid (Ki 1.4 nM). This is the same target as SSRI antidepressants. ^{6 8}	Laboratory research
Phosphodiesterase 4 (PDE4)	PDE4	The extract inhibited PDE4 (IC50 8.5 ug/mL) but not other phosphodiesterases; mesembrenone inhibited PDE4 at under 1 uM. ^{6 8}	Laboratory research
Threat circuitry of the brain (amygdala)	Not specified	In 16 healthy people, one dose of Zembrin lowered amygdala reactivity to fearful faces and amygdala-hypothalamus coupling. ¹⁹	Human data
Monoamine release (high-mesembrine extract)	Serotonin transporter expression	One high-mesembrine extract (Trimesemine) was reported in vitro to reduce transporter expression like citalopram and to act as a monoamine releasing agent, not only a reuptake blocker. ²	Laboratory research
Mood and anxiety behaviour in animals	Not specified	A 2026 review concludes animal studies of antidepressant and anxiolytic effects are mixed. ²¹	Animal research

Absorption, metabolism and elimination

Absorption: In pig tissue in a dish, mesembrine crossed intestinal tissue faster than caffeine; mesembrenone and mesembrenol more slowly; tissue in the mouth was less permeable but may add to absorption when the plant is chewed and held in the mouth for a long time.
Distribution: Not covered in the sources read.
Metabolism: In rats and human liver preparations, both main alkaloids were O- and N-demethylated, dihydrated and/or hydroxylated, and partly conjugated to glucuronides or sulfates.
Elimination: Metabolites appear in rat urine and could be detected in urine screens if human kinetics are similar; human elimination time was not found.
Bioavailability: No human pharmacokinetic study was found in the sources read.

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Isolated compounds versus whole extracts

Several different things are sold as kanna. (1) Traditionally fermented dried aerial parts, chewed, smoked or made into tea or tincture. (2) Dried unfermented plant. (3) Zembrin, a standardized 2:1 ethanol-water extract of a mild ('mak') variety, with 0.35 to 0.45% total alkaloids, mostly mesembrenone and mesembrenol with under 20% mesembrine. (4) Other extracts with higher mesembrine (for example Trimesemine). (5) Powders, vapes and gummies of unknown strength. Nearly all human trials used Zembrin, so their results cannot be carried over to the others. Fermentation changes the plant's chemistry, but whether it makes it stronger is unsettled, and no human study compares fermented with unfermented.

Nutritional composition

Kanna is a psychoactive medicinal and recreational plant, not a food source of nutrients.

8benefits and uses looked at

21studies and sources checked

Very low certaintybest evidence rating found

8lab markers tracked in trials

4 very low certainty4 not enough evidence

What was looked at

The 8 benefits and uses checked for Kanna (Sceletium tortuosum), each with how strong the evidence is. Tap one to open it.

Anxiety and stress under laboratory pressure (Zembrin, healthy young adults)Very low certainty
Brain response to threatening faces (amygdala imaging, Zembrin)Very low certainty
Thinking skills in healthy middle-aged adults (Zembrin)Very low certainty
Low mood and depressionNot enough evidence
Sleep and sense of well-beingNot enough evidence
Reaction speed and visual tracking in trained young adultsVery low certainty
Pain, toothache, stomach upset, colic and alcohol misuse (traditional uses only)Not enough evidence
Immune, inflammation and other lab findings (no human studies)Not enough evidence

Lab markers tracked in the studies

Amygdala response to fearful faces (fMRI)Self-reported anxiety under laboratory stressHeart rate during laboratory stressCognitive flexibility and executive function scoresDepression rating scale in healthy adults (HAM-D)Complex reactive agility and visual trackingTotal mood score (Profile of Mood States)Vital signs, ECG, blood and urine tests over 3 months

What is Kanna (Sceletium tortuosum) good for?

The main studied uses and how strong the human evidence is for each. All of it is very small and most is linked to the maker of one extract. Treat these as early findings.

Anxiety and stress under laboratory pressure (Zembrin, healthy young adults)Very low certaintyTwo small studies in 20 healthy volunteers found no effect on mood in one and lower reported anxiety before a speaking task in the other. Authors call it tentative; nobody with an anxiety disorder was studied. Brain response to threatening facesVery low certaintyIn 16 healthy people, one dose of Zembrin lowered the brain's amygdala response to fearful faces. This is a brain-scan finding, not a symptom result. Thinking skills in healthy middle-aged adultsVery low certaintyA 21-person crossover trial found better cognitive flexibility and executive function than placebo after 3 weeks. It was small, tested several outcomes, and involved authors from the extract maker. Reaction speed in trained young adultsVery low certaintyIn 60 fit adults after 8 days, complex reaction tasks improved but simple reaction, alertness and mood did not. Low mood and depressionNot enough evidenceTraditional use and lab serotonin effects, but no trial in people with depression. Mood results in healthy people are mixed. It should not replace prescribed treatment. Sleep and sense of well-beingNot enough evidenceSome healthy participants noted better sleep or coping in diaries or secondary results. No planned sleep testing was done. Pain, toothache, stomach upset, colic and alcohol misuse (traditional only)Not enough evidenceOld traditional uses. No human trials were found. Giving kanna to babies or children on the basis of tradition is not supported by any safety evidence.

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.

Anxiety and stress under laboratory pressure (Zembrin, healthy young adults)

Very low certainty

Two tiny studies of 20 healthy volunteers gave one dose of a branded extract before a stressful task. One showed no effect; the other showed lower reported anxiety before a speaking task. The authors call it tentative.

3 studiesZembrin standardized extract only. Results cannot be applied to dried…

Studies, doses and limits

What the trials found

Reay 2020 reported two placebo-controlled studies in 20 young healthy people. Study 1 (a 20-minute multitasking stress task) found no treatment effect. Study 2 (a 5-minute simulated speech) found lower subjective anxiety before the stress and a treatment-by-time effect on heart rate. A 2026 review concluded that evidence is mixed, with small samples and healthy rather than anxious people. No trial has tested kanna in people with an anxiety disorder.

Results

One null study and one small positive result on a pre-stress measure, single dose only.

Effect sizes as reported

No effect sizes given in the abstract (study 2: significantly lower pre-stress anxiety and a treatment-by-time effect on heart rate).

Why this rating

Twenty people in total, a single dose, one of the two studies was null, healthy volunteers, and a co-author is linked to the extract's marketers.

Form and dose studied

Zembrin standardized extract only. Results cannot be applied to dried kanna, teas, vapes or other products.

Who was studied

Healthy young adults; no people with anxiety disorders.

Limits

Very small; single dose; laboratory stress is not real-life anxiety; no long-term data; one research network.

Why researchers looked

Kanna was traditionally used to calm and lift mood, and lab tests show it acts on serotonin handling in the brain.

Traditional use

Kanna (kougoed, 'chewing stuff') was chewed, smoked, or made into tea or tincture by the Khoikhoi and San peoples of South Africa as a mood lifter, sedative and pain reliever, and also for intoxication (reviews of historical sources).

Proposed mechanism Laboratory research

In lab tests, Zembrin and its alkaloids block the serotonin transporter and the enzyme PDE4. Whether this explains any human effect is not shown. Lab and animal work only.

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

Open the Safety tab first, especially if you take antidepressants or other serotonin-acting medicines.

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Brain response to threatening faces (amygdala imaging, Zembrin)

Very low certainty

In a brain-scan study of 16 healthy people, one dose of Zembrin lowered the amygdala's response to fearful faces. This is a brain-activity finding, not proof that anyone felt less anxious.

2 studiesZembrin standardized extract, single dose.

Studies, doses and limits

What the trials found

Terburg 2013 was a double-blind, placebo-controlled crossover study in 16 healthy volunteers using brain scanning. After a single dose, amygdala reactivity to fearful faces (under low perceptual load) was lower and amygdala-hypothalamus coupling was reduced.

Results

Lower amygdala reactivity and coupling after one dose.

Effect sizes as reported

Not given in the abstract.

Why this rating

16 people, one dose, an imaging outcome rather than symptoms, and a co-author is linked to the extract maker in other papers read.

Form and dose studied

Zembrin standardized extract, single dose.

Who was studied

Healthy adults.

Limits

Imaging markers do not equal symptom relief; no replication found in this search.

Why researchers looked

The amygdala is a brain region involved in reacting to threat; many anxiety medicines change its activity.

Traditional use

Proposed mechanism Preliminary mechanism

The authors link the result to the extract's lab actions on the serotonin transporter and PDE4. This is a hypothesis.

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

No safety problems were reported in the abstract, but it was a single dose.

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Thinking skills in healthy middle-aged adults (Zembrin)

Very low certainty

In a small 3-week crossover trial of 21 healthy adults (average age about 55), Zembrin scored better than placebo on cognitive flexibility and executive function tests.

2 studiesZembrin standardized extract capsule.

Studies, doses and limits

What the trials found

Chiu 2014 randomised 21 cognitively healthy adults to Zembrin or placebo in a double-blind crossover design with 3-week periods. Zembrin improved cognitive set flexibility (P < 0.032) and executive function (P < 0.022) on a computerised battery. The authors also reported positive changes in mood and sleep. Hoffman 2020 (see the other health uses) found better complex reaction performance in young trained adults. The 2026 review lists cognition among outcomes with possible benefit but not consistent results.

Results

Better flexibility and executive function scores versus placebo.

Effect sizes as reported

Set flexibility P < 0.032; executive function P < 0.022 (effect sizes not in the abstract).

Why this rating

One small trial of 21 people with several outcomes tested, healthy volunteers, authors from the extract maker.

Form and dose studied

Zembrin standardized extract capsule.

Who was studied

Healthy adults, average age 54.6; not people with memory problems.

Limits

Small, short, multiple outcomes, no patient group; the Alzheimer's implication in the title is a hope, not a finding.

Why researchers looked

PDE4 is involved in memory signalling in the brain, and the extract blocks PDE4 in lab tests.

Traditional use

Traditional users also described kanna as improving memory and general well-being (review of traditional uses).

Proposed mechanism Pharmacological theory

PDE4 inhibition and cAMP signalling is the authors' proposed explanation; it was not measured in the trial.

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

Well tolerated over the 3-week periods according to the abstract.

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Low mood and depression

Not enough evidence

Kanna has a long reputation as a mood lifter, but no trial has tested it in people with depression. Trials in healthy people give mixed mood results.

7 studiesNot established.

Studies, doses and limits

What the trials found

The 2021 review states the plant has not yet been studied in a clinical (patient) population. In the 8-day Hoffman trial of 60 trained adults there was no difference in total mood score. In the Chiu trial the authors reported positive mood changes in healthy adults. The 2026 review judged the antidepressant and anxiolytic evidence as mixed. A reported nickname online of 'nature's MDMA' is not supported: a consumer reference says it is unclear whether recreational kanna causes a high.

Results

No depression trial; mixed mood results in healthy people.

Effect sizes as reported

Not applicable.

Why this rating

No trials in people with depression; mood outcomes in healthy people are mixed and small.

Form and dose studied

Not established.

Who was studied

No depressed patients studied.

Limits

Do not use kanna in place of prescribed treatment. The same serotonin action creates interaction risks with antidepressants.

Why researchers looked

Traditional mood use, and lab evidence that it blocks the serotonin transporter, the same target as SSRI antidepressants.

Traditional use

Proposed mechanism Laboratory research

Serotonin transporter blocking in lab tests (mesembrine most potent). A separate in-vitro study of one high-mesembrine extract described it as acting as a monoamine releasing agent.

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

Serotonin-acting medicines and MAOIs are the main concern; see the Safety tab.

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Sleep and sense of well-being

Not enough evidence

Some participants in two trials noted better sleep or coping with stress, but these were diary notes or secondary findings, not planned tests of sleep.

3 studiesZembrin in both trials.

Studies, doses and limits

What the trials found

In the 3-month safety trial of 37 healthy adults (Nell 2013) no efficacy outcomes were measured, but some participants wrote in diaries about better coping with stress and sleep. Chiu 2014 reported positive changes in mood and sleep. No sleep study with proper sleep measures was found.

Results

Unplanned positive notes only.

Effect sizes as reported

Not available.

Why this rating

Not a planned outcome; anecdotal diary notes and a secondary finding.

Form and dose studied

Zembrin in both trials.

Who was studied

Healthy adults.

Limits

No sleep testing; participants knew what they felt.

Why researchers looked

Kanna was traditionally used as a sedative and for insomnia.

Traditional use

Historical accounts describe a tea or tincture used as a sedative; healers also used it for insomnia (review of traditional uses).

Proposed mechanism Preliminary mechanism

Not studied for sleep.

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

Kanna is described as sedating traditionally; take care with alcohol and sedatives (see the Safety tab).

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Reaction speed and visual tracking in trained young adults

Very low certainty

In an 8-day trial of 60 fit adults aged 20 to 35, an extract improved performance on complex reaction tasks that require thinking, but not simple reaction speed, alertness or mood.

2 studiesA standardized S. tortuosum extract; the abstract does not name the b…

Studies, doses and limits

What the trials found

Hoffman 2020 randomised 60 recreationally trained men and women to a Sceletium tortuosum extract or placebo for 8 days and tested them 2 hours after the day-8 dose. Complex reactive performance with a cognitive load was better with the extract. No differences were seen in simple reaction, the alertness and energy scale, or total mood score. The 2026 review notes some outcomes were limited to reaction time under cognitive stress.

Results

Better complex reaction performance; no mood or simple-reaction benefit.

Effect sizes as reported

Not given in the abstract.

Why this rating

One small, short trial in young fit people; the brand and funding are not stated in the abstract.

Form and dose studied

A standardized S. tortuosum extract; the abstract does not name the brand.

Who was studied

Recreationally trained adults aged 20-35.

Limits

Single trial, tested once after the last dose, no long-term data.

Why researchers looked

A sense of well-being and mental sharpness is reported for kanna; researchers tested it in healthy young people.

Traditional use

Traditional users reported less fatigue, more endurance and reduced hunger and thirst (review of traditional uses).

Proposed mechanism Pharmacological theory

Not established; the same serotonin transporter and PDE4 actions seen in the lab may be involved.

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

No safety signal is reported in the abstract. See the Safety tab for medicines to avoid.

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Pain, toothache, stomach upset, colic and alcohol misuse (traditional uses only)

Not enough evidence

Kanna was traditionally used for pain, toothache, stomach cramps, colic in babies and to ease alcohol misuse. No human trial for any of these was found.

2 studiesTraditional fermented plant, chewed or smoked, tea or tincture.

Studies, doses and limits

What the trials found

No clinical trial for pain, digestion or alcohol misuse was found in the sources read. The 2021 review lists many lab and animal findings (antioxidant, immune-modulating, antimalarial, anti-HIV and brain-protective activities) but they are laboratory and animal results only.

Results

No human data.

Effect sizes as reported

Not applicable.

Why this rating

Only traditional use and lab or animal work.

Form and dose studied

Traditional fermented plant, chewed or smoked, tea or tincture.

Who was studied

No trial populations.

Limits

Do not give kanna to children or infants on the basis of tradition. No source read supports its safety there.

Why researchers looked

These are old uses recorded in historical sources, not tested uses.

Traditional use

Reviews of historical sources list pain, headache, toothache, nausea, colic, abdominal cramps, constipation, asthma, thirst and hunger suppression, and treating alcoholism. Healers in Namaqualand use it for alcohol misuse. A small amount added to breast milk has been given to infants for colic. This is a record of practice, not evidence of safety.

Proposed mechanism Traditional use

No human mechanism for these uses has been tested.

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

Pregnancy, breastfeeding and children: see the Safety tab.

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Immune, inflammation and other lab findings (no human studies)

Not enough evidence

Cell and animal studies point to antioxidant and immune effects of kanna extracts. None has been tested in people for these purposes.

1 studiesNot applicable.

Studies, doses and limits

What the trials found

No human studies for these outcomes. The 2021 review describes them as in vitro or in vivo (animal) results.

Results

Not applicable.

Effect sizes as reported

Not applicable.

Why this rating

No human data.

Form and dose studied

Not applicable.

Who was studied

None.

Limits

Cell and animal results often do not carry over to people.

Why researchers looked

Researchers screened the extracts for many possible activities.

Traditional use

Not a traditional use.

Proposed mechanism Laboratory research

Laboratory and animal findings only (antioxidant, immune-modulating and neuroprotective activity in cells and animals).

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

None.

¹⁴

Connections to the rest of health

How Kanna (Sceletium tortuosum) 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
Anxiety Support	Potential benefit	Very low certainty	Anxiety and stress under laboratory pressure (Zembrin, healthy young adults): Two tiny studies of 20 healthy volunteers gave one dose of a branded extract before a stressful task. One showed no effect; the other showed lower reported anxiety before a speaking task. The authors call it tentative.	^{17 21 6}
Stress Reduction	Potential benefit	Very low certainty	Anxiety and stress under laboratory pressure (Zembrin, healthy young adults): Two tiny studies of 20 healthy volunteers gave one dose of a branded extract before a stressful task. One showed no effect; the other showed lower reported anxiety before a speaking task. The authors call it tentative.	^{17 21 6}
Calm Relaxation	Potential benefit	Very low certainty	Anxiety and stress under laboratory pressure (Zembrin, healthy young adults): Two tiny studies of 20 healthy volunteers gave one dose of a branded extract before a stressful task. One showed no effect; the other showed lower reported anxiety before a speaking task. The authors call it tentative.	^{17 21 6}
Anxiety Support	Preliminary mechanism	Very low certainty	Brain response to threatening faces (amygdala imaging, Zembrin): In a brain-scan study of 16 healthy people, one dose of Zembrin lowered the amygdala's response to fearful faces. This is a brain-activity finding, not proof that anyone felt less anxious.	^{19 21}
Brain Health	Preliminary mechanism	Very low certainty	Brain response to threatening faces (amygdala imaging, Zembrin): In a brain-scan study of 16 healthy people, one dose of Zembrin lowered the amygdala's response to fearful faces. This is a brain-activity finding, not proof that anyone felt less anxious.	^{19 21}
Cognitive Performance	Potential benefit	Very low certainty	Thinking skills in healthy middle-aged adults (Zembrin): In a small 3-week crossover trial of 21 healthy adults (average age about 55), Zembrin scored better than placebo on cognitive flexibility and executive function tests.	^{4 21}
Mental Clarity	Potential benefit	Very low certainty	Thinking skills in healthy middle-aged adults (Zembrin): In a small 3-week crossover trial of 21 healthy adults (average age about 55), Zembrin scored better than placebo on cognitive flexibility and executive function tests.	^{4 21}
Memory Support	Potential benefit	Very low certainty	Thinking skills in healthy middle-aged adults (Zembrin): In a small 3-week crossover trial of 21 healthy adults (average age about 55), Zembrin scored better than placebo on cognitive flexibility and executive function tests.	^{4 21}
Mood Balance	Traditional use	Not enough evidence	Low mood and depression: Kanna has a long reputation as a mood lifter, but no trial has tested it in people with depression. Trials in healthy people give mixed mood results.	^{14 21 7 4 6 2 20}
Better Sleep	Traditional use	Not enough evidence	Sleep and sense of well-being: Some participants in two trials noted better sleep or coping with stress, but these were diary notes or secondary findings, not planned tests of sleep.	^{13 4 2}
Sleep Quality	Traditional use	Not enough evidence	Sleep and sense of well-being: Some participants in two trials noted better sleep or coping with stress, but these were diary notes or secondary findings, not planned tests of sleep.	^{13 4 2}
Stress Reduction	Traditional use	Not enough evidence	Sleep and sense of well-being: Some participants in two trials noted better sleep or coping with stress, but these were diary notes or secondary findings, not planned tests of sleep.	^{13 4 2}
Peak Performance	Potential benefit	Very low certainty	Reaction speed and visual tracking in trained young adults: In an 8-day trial of 60 fit adults aged 20 to 35, an extract improved performance on complex reaction tasks that require thinking, but not simple reaction speed, alertness or mood.	^{7 21}
Better Focus	Potential benefit	Very low certainty	Reaction speed and visual tracking in trained young adults: In an 8-day trial of 60 fit adults aged 20 to 35, an extract improved performance on complex reaction tasks that require thinking, but not simple reaction speed, alertness or mood.	^{7 21}
Physical Stamina	Potential benefit	Very low certainty	Reaction speed and visual tracking in trained young adults: In an 8-day trial of 60 fit adults aged 20 to 35, an extract improved performance on complex reaction tasks that require thinking, but not simple reaction speed, alertness or mood.	^{7 21}
Digestive Support	Traditional use	Not enough evidence	Pain, toothache, stomach upset, colic and alcohol misuse (traditional uses only): Kanna was traditionally used for pain, toothache, stomach cramps, colic in babies and to ease alcohol misuse. No human trial for any of these was found.	^{2 14}
Calm Relaxation	Traditional use	Not enough evidence	Pain, toothache, stomach upset, colic and alcohol misuse (traditional uses only): Kanna was traditionally used for pain, toothache, stomach cramps, colic in babies and to ease alcohol misuse. No human trial for any of these was found.	^{2 14}
Immune Support	Preliminary mechanism	Not enough evidence	Immune, inflammation and other lab findings (no human studies): Cell and animal studies point to antioxidant and immune effects of kanna extracts. None has been tested in people for these purposes.	¹⁴
Inflammation Balance	Preliminary mechanism	Not enough evidence	Immune, inflammation and other lab findings (no human studies): Cell and animal studies point to antioxidant and immune effects of kanna extracts. None has been tested in people for these purposes.	¹⁴

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Nervous system	Adverse effect or risk	Not enough evidence	Psychoactive plant with traditional sedative and intoxicating use; drowsiness and trouble concentrating reported. Preparation or compound: Kanna alkaloids	^{15 2}
Nervous system	Contraindication	Not enough evidence	A drug reference advises caution; no data. Preparation or compound: Whole kanna in people with psychosis or past suicide attempt	²⁰
Nervous System	Biological association	Very low certainty	Studied for: Anxiety and stress under laboratory pressure (Zembrin, healthy young adults) Studied for: Brain response to threatening faces (amygdala imaging, Zembrin)	^{17 21 6 19 4 14 7 2 20}
Stress Mood	Biological association	Very low certainty	Studied for: Anxiety and stress under laboratory pressure (Zembrin, healthy young adults) Studied for: Low mood and depression	^{17 21 6 14 7 4 2 20 13}
Sleep Recovery	Biological association	Not enough evidence	Studied for: Sleep and sense of well-being	^{13 4 2}
Digestive System	Biological association	Not enough evidence	Studied for: Pain, toothache, stomach upset, colic and alcohol misuse (traditional uses only)	^{2 14}
Immune System	Biological association	Not enough evidence	Studied for: Immune, inflammation and other lab findings (no human studies)	¹⁴

G. Root causes and contributing factors

Connected to	Kind of connection	Evidence status	Context	Studies
Medication side effects	Drug or supplement interaction	Not enough evidence	Lab serotonin-transporter blocking plus drug-reference warnings; no human interaction study. Preparation or compound: Kanna with serotonin-acting medicines	^{6 20}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Amygdala response to fearful faces (fMRI)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁹
Self-reported anxiety under laboratory stress	Biological association	Very low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	¹⁷
Heart rate during laboratory stress	Biological association	Very low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	¹⁷
Cognitive flexibility and executive function scores	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	⁴
Depression rating scale in healthy adults (HAM-D)	Biological association	Not enough evidence	Measured in trials: mixed. A lab change is not the same as a health benefit.	⁴
Complex reactive agility and visual tracking	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	⁷
Total mood score (Profile of Mood States)	Biological association	Very low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	⁷
Vital signs, ECG, blood and urine tests over 3 months	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	¹³

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
PDE4 (phosphodiesterase 4)	Preliminary mechanism	In vitro	Inhibited by the extract and mesembrenone in lab tests; proposed link to memory signalling (cAMP-CREB) is a hypothesis.	^{6 4}

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Serotonin transporter (SERT, SLC6A4)	Preliminary mechanism	In vitro	Blocked by kanna extract and mesembrine in lab tests; the basis of the antidepressant-interaction caution.	⁶
Amygdala	Preliminary mechanism	Human	Reduced response to fearful faces after one dose in 16 healthy people.	¹⁹

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Mesembrine	Biological association	In vitro	Most potent serotonin-transporter blocker among the alkaloids tested (Ki 1.4 nM in a lab binding test). Preparation or compound: Aerial parts	^{6 11 16}
Mesembrenone	Biological association	In vitro	Acts on both the serotonin transporter and PDE4 (IC50 below 1 uM) in lab tests. Preparation or compound: Aerial parts	^{6 11 16}
Mesembrenol	Biological association	In vitro	Tested with the other alkaloids in the lab; less potent details not extracted from the abstract. Preparation or compound: Aerial parts	^{6 11}
Hordenine	Biological association	In vitro	Stimulant-like compound found naturally in kanna; also reported as an added ingredient in some products. Its effect in people from kanna is not established. Preparation or compound: Aerial parts	^{1 15 16}
Other alkaloid classes (Sceletium A4, joubertiamine, tortuosamine)	Biological association	In vitro	Not detailed in the sources read. Preparation or compound: Aerial parts	¹⁴

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 8 lab markers

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

Other1223

The evidence

The research centre for Kanna (Sceletium tortuosum). Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Anxiety and stress under laboratory pressure (Zembrin, healthy young adults) 3 studies · 20 people in trials Very low certainty Brain response to threatening faces (amygdala imaging, Zembrin) 2 studies · 16 people in trials Very low certainty Thinking skills in healthy middle-aged adults (Zembrin) 2 studies · 21 people in trials Very low certainty Low mood and depression 7 studies · 81 people in trials Not enough evidence Sleep and sense of well-being 3 studies · 58 people in trials Not enough evidence Reaction speed and visual tracking in trained young adults 2 studies · 60 people in trials Very low certainty Pain, toothache, stomach upset, colic and alcohol misuse (traditional uses only) 2 studies Not enough evidence Immune, inflammation and other lab findings (no human studies) 1 studies Not enough evidence

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 abstract of every PubMed study cited, read the full text of a 2021 regulatory review (Brendler), the WebMD and Operation Supplement Safety pages, and checked plant names in GBIF and NCBI Taxonomy and compound records in PubChem. EMA and NCCIH were checked and no kanna page was found.

Study library: every study we checked 21

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
Appley 2022 Quantification of hordenine in a complex plant matrix by direct analysis in real time-high-resolution mass spectrometry: Application to the 'plant of concern' Sceletium tortuosum. Drug Test Anal · PMID 34750996 · DOI	Laboratory in-vitro	6 Six commercial products from S. tortuosum foliage and stems	Commercial S. tortuosum products stems and leaves Not applicable Not applicable · vs Not applicable	Hordenine ranged from 0.02738 to 1.071 mg per gram of plant material across six products; the UN Office on Drugs and Crime lists S. tortuosum as a 'plant of concern'. 0.027-1.07 mg/g (about 40-fold range) Methods, limits and funding Outcomes: Hordenine content by mass spectrometry Limitations: Six products only; method paper. Funding and conflicts: Not stated in the abstract record. Read: abstract
Brendler 2021 Sceletium for Managing Anxiety, Depression and Cognitive Impairment: A Traditional Herbal Medicine in Modern-Day Regulatory Systems. Curr Neuropharmacol · PMID 33588735 · DOI	Review	Case study of how M. tortuosum aerial parts are regulated in the EU, USA, Australia, Canada, Russia and South Africa	M. tortuosum aerial parts and extracts (Zembrin, Trimesemine) aerial parts Not applicable Not applicable · vs Not applicable	Describes traditional use, preparation, regulatory routes and barriers in each region; states there were no legal sceletium products in the EU market at the time of writing; Russian list prohibits mesembrine; Australia had not listed it. Descriptive Methods, limits and funding Outcomes: Regulatory status and traditional use Limitations: Regulatory position is as of about 2020-2021 and may have changed. Authors include people working for herbal-product companies; the conflict-of-interest statement was not read. Funding and conflicts: Author affiliations include industry (Traditional Medicinals, Parceval (Pty) Ltd); funding not checked. Read: full-text
Brunetti 2020 Pharmacology of Herbal Sexual Enhancers: A Review of Psychiatric and Neurological Adverse Effects. Pharmaceuticals (Basel) · PMID 33066617 · DOI	Review	Review of 15 herbal aphrodisiacs including S. tortuosum	Herbal aphrodisiacs, including S. tortuosum Not stated Not applicable Not applicable · vs Not applicable	Across the plants, most appeared safe at therapeutic amounts, but mild to severe effects can occur with overdosing or unstandardised products; drug interactions are the larger concern; few data exist for several plants. Narrative Methods, limits and funding Outcomes: Psychiatric and neurological adverse effects Limitations: The abstract does not separate out S. tortuosum findings, so no kanna-specific conclusion is drawn. Funding and conflicts: No conflicts declared (abstract record). Read: abstract
Chiu 2014 Proof-of-Concept Randomized Controlled Study of Cognition Effects of the Proprietary Extract Sceletium tortuosum (Zembrin) Targeting Phosphodiesterase-4 in Cognitively Healthy Subjects: Implications for Alzheimer's Dementia. Evid Based Complement Alternat Med · PMID 25389443 · DOI	Controlled trial	21 21 cognitively healthy adults (mean age 54.6), 9 men and 12 women	Zembrin standardized S. tortuosum extract aerial parts 25 mg capsule once daily 3 weeks each period (crossover) · vs Placebo capsule	Better cognitive set flexibility (P < 0.032) and executive function (P < 0.022) than placebo; positive changes in mood and sleep reported; well tolerated. Set flexibility P < 0.032; executive function P < 0.022 Methods, limits and funding Outcomes: Computerised cognitive tests (CNS Vital Signs), Hamilton depression scale, side effects Limitations: 21 people, 3-week periods, healthy volunteers; the conclusion about Alzheimer's is speculation. Authors include HG&H Pharmaceuticals staff (the extract maker) and a P L Thomas & Co. author. Funding and conflicts: Authors affiliated with HG&H Pharmaceuticals (Pty) Ltd and P L Thomas & Co.; funding source not stated in the abstract. Registration: NCT01805518 Read: abstract
GBIF 2026 GBIF Backbone Taxonomy: Mesembryanthemum tortuosum L. GBIF · Source	Database record	General readers	Sceletium tortuosum / kanna leaves and aerial parts Not applicable Not applicable · vs Not applicable	GBIF key 7750120 Mesembryanthemum tortuosum L. is ACCEPTED (family Aizoaceae, order Caryophyllales); Sceletium tortuosum (L.) N.E.Br. (key 3707372) is a SYNONYM pointing to it. Checked by API 2026-10-25. n/a Methods, limits and funding Outcomes: Uses, safety, interactions Limitations: Database record. Read: full-text
Harvey 2011 Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids. J Ethnopharmacol · PMID 21798331 · DOI	Laboratory research in-vitro	Cell-free and cell tests of Zembrin and three alkaloids on drug targets	Zembrin ethanolic extract; purified mesembrine, mesembrenone, mesembrenol aerial parts Not applicable (laboratory) Not applicable · vs Not applicable	Extract blocked the serotonin (5-HT) transporter (IC50 4.3 ug/mL) and PDE4 (IC50 8.5 ug/mL) but not other phosphodiesterases; mesembrine was the most active at the serotonin transporter (Ki 1.4 nM); mesembrenone acted on both the transporter and PDE4 (IC50 below 1 uM); no cytotoxic effects. Transporter IC50 4.3 ug/mL; PDE4 IC50 8.5 ug/mL Methods, limits and funding Outcomes: Binding to receptors, enzymes and transporters; cell toxicity Limitations: Laboratory only. Co-author N. Gericke is linked to the extract maker. Funding and conflicts: Not stated in the abstract record. Read: abstract
Hoffman 2020 Ergogenic Effects of 8 Days of Sceletium Tortuosum Supplementation on Mood, Visual Tracking, and Reaction in Recreationally Trained Men and Women. J Strength Cond Res · PMID 32740286 · DOI	Controlled trial	60 60 recreationally trained adults aged 20-35 (48 men, 12 women)	S. tortuosum extract (brand not named in the abstract; a US military guidance page says the human trials used Zembrin) aerial parts 25 mg 8 days; tested 2 hours after the day-8 dose · vs Placebo	Better performance on complex reactive tasks with a cognitive load; no difference in simple reaction, alertness/energy scale or total mood score. Better complex reactive performance (statistics not in the abstract); mood no change Methods, limits and funding Outcomes: Reactive agility, visual tracking, alertness/energy scale, Profile of Mood States Limitations: Small, short, young fit adults; the brand and funding are not stated in the abstract. Funding and conflicts: Not stated in the abstract record. Read: abstract
Krstenansky 2017 Mesembrine alkaloids: Review of their occurrence, chemistry, and pharmacology. J Ethnopharmacol · PMID 27939420 · DOI	Review in-vitro	Review of mesembrine alkaloids	Mesembrine and mesembrenone aerial parts Not applicable Not applicable · vs Not applicable	Mesembrine and mesembrenone are the two major active alkaloids and are serotonin reuptake inhibitors; mesembrenone also has reasonably potent PDE4 inhibitory activity; their pharmacology is still being characterised. Narrative Methods, limits and funding Outcomes: Occurrence, chemistry and pharmacology Limitations: Narrative review of mostly laboratory work. Funding and conflicts: Not stated in the abstract record. Read: abstract
Lesiak 2016 Direct analysis in real time high resolution mass spectrometry as a tool for rapid characterization of mind-altering plant materials and revelation of supplement adulteration - The case of Kanna. Forensic Sci Int · PMID 26821203 · DOI	Laboratory in-vitro	Commercially available kanna products tested by mass spectrometry	Commercial S. tortuosum (kanna) products Not stated Not applicable Not applicable · vs Not applicable	Products were identified as kanna by their alkaloids (including hordenine); the stimulant ephedrine, banned in herbal products and supplements, was confirmed in one sample. Ephedrine in one sample Methods, limits and funding Outcomes: Identification of alkaloids and adulterants Limitations: The abstract does not say how many products were tested; this shows adulteration can happen, not how often. Funding and conflicts: Not stated in the abstract record. Read: abstract
Meyer 2015 GC-MS, LC-MS(n), LC-high resolution-MS(n), and NMR studies on the metabolism and toxicological detection of mesembrine and mesembrenone, the main alkaloids of the legal high 'Kanna' isolated from Sceletium tortuosum. Anal Bioanal Chem · PMID 25240931 · DOI	Animal research animal	Rat urine and pooled human liver preparations	Mesembrine and mesembrenone isolated from S. tortuosum aerial parts Rat low-dose application (user-like) Not applicable · vs Not applicable	Both alkaloids were O- and N-demethylated, dihydrated and/or hydroxylated; phenolic metabolites were partly excreted as glucuronides or sulfates; most phase I metabolites in rats also appeared in human liver preparations; use should be detectable in urine drug screens, assuming similar human kinetics. Qualitative Methods, limits and funding Outcomes: Metabolites and urine detectability Limitations: Rat and liver-preparation work; human pharmacokinetics were not measured. Funding and conflicts: Not stated in the abstract record. Read: abstract
Murbach 2014 A toxicological safety assessment of a standardized extract of Sceletium tortuosum (Zembrin) in rats. Food Chem Toxicol · PMID 25301237 · DOI	Animal research animal	Wistar rats, 14-day and 90-day oral studies	Zembrin hydroethanolic extract (0.35-0.45% total alkaloids; mesembrenone + mesembrenol at least 60%, mesembrine under 20%; a 'mak' (mild) variety) aerial parts Rat studies up to 5000 mg/kg (14 days) and 600 mg/kg (90 days) 14 and 90 days · vs Vehicle control	No deaths or treatment-related adverse effects; no-observed-adverse-effect levels were the highest doses tested (5000 mg/kg/day for 14 days; 600 mg/kg/day for 90 days). NOAEL 5000 and 600 mg/kg/day Methods, limits and funding Outcomes: Mortality, toxicity signs, behaviour, locomotion Limitations: Rats, one extract only; the rat result does not give a human safe amount. Authors include HG&H Pharmaceuticals staff. Funding and conflicts: Authors from AIBMR Life Sciences, Toxi-Coop and HG&H Pharmaceuticals (the extract maker); funding presumed industry but not stated in the abstract. Read: abstract
NCBI Taxonomy 2026 NCBI Taxonomy: Mesembryanthemum tortuosum (taxid 216016) NCBI Taxonomy · Source	Database record	General readers	Sceletium tortuosum / kanna leaves and aerial parts Not applicable Not applicable · vs Not applicable	Species Mesembryanthemum tortuosum, taxid 216016; Sceletium tortuosum listed as a synonym; lineage Caryophyllales; Aizoaceae; Mesembryanthemum. Checked through the NCBI API 2026-10-25. n/a Methods, limits and funding Outcomes: Uses, safety, interactions Limitations: Database record. Read: full-text
Nell 2013 A randomized, double-blind, parallel-group, placebo-controlled trial of Extract Sceletium tortuosum (Zembrin) in healthy adults. J Altern Complement Med · PMID 23441963 · DOI	Controlled trial	37 37 healthy adults in South Africa	Zembrin standardized 2:1 S. tortuosum extract aerial parts 8 mg or 25 mg once daily 3 months · vs Identical placebo	No apparent differences in vital signs, ECG, weight, physical exam, haematology or biochemistry; both amounts well tolerated; headache was the most common adverse event, followed by abdominal pain and upper respiratory infections, all more often in the placebo group; some participants noted unsolicited positive effects on well-being, coping with stress and sleep. No safety signal in 37 healthy people over 3 months Methods, limits and funding Outcomes: Safety and tolerability: vital signs, ECG, blood tests, adverse events (no efficacy outcomes) Limitations: Only 12-13 people per group; healthy adults; the longest human trial found; no efficacy outcomes were measured; co-author Gericke is linked to the extract maker. Funding and conflicts: Not stated in the abstract record; co-author N. Gericke is linked to HG&H Pharmaceuticals in other papers read. Read: abstract
Olatunji 2021 Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological and clinical activities. J Ethnopharmacol · PMID 34333104 · DOI	Review	Literature review of plant chemistry, animal/lab work and clinical studies (publications 2009-2021 for pharmacology)	S. tortuosum extracts and alkaloids aerial parts Not applicable Not applicable · vs Not applicable	25 alkaloids in four classes, mesembrine class predominant; wide range of lab/animal activities; authors state the plant has not yet been studied in a clinical (patient) population but has potential for cognition, anxiety and depression. Narrative Methods, limits and funding Outcomes: Phytochemistry, pharmacokinetics, biological and clinical activities Limitations: Narrative review; an erratum was published (J Ethnopharmacol 2022;287:114711) and was not read; some authors work at the university group that studies Zembrin. Funding and conflicts: Not stated in the abstract record. Read: abstract
Operation Supplement Safety (US Department of Defense / Uniformed Services University) 2025 Kanna: Uses and Safety in Dietary Supplements Operation Supplement Safety (US Department of Defense / Uniformed Services University) · Source	Authoritative guidance	General readers	Sceletium tortuosum / kanna leaves and aerial parts Not applicable Not applicable · vs Not applicable	A few small studies in healthy people suggest possible effects on anxiety, mood, stress or sleep, all using Zembrin; side effects in studies included headache, stomach problems, fatigue, drowsiness and trouble concentrating; products have been reported adulterated with hordenine and ephedrine; kanna is not on the DoD prohibited list but service policies bar substances used to get high; recreational (vaping, snorting, with cannabis) risks are unknown. Content current as of 15 December 2025. n/a Methods, limits and funding Outcomes: Uses, safety, interactions Limitations: Military-supplement guidance; reference list overlaps with the studies read here. Read: full-text
PubChem 2026 PubChem records: mesembrine (CID 394162), mesembrenone (CID 216272), hordenine (CID 68313) PubChem · Source	Database record	General readers	Sceletium tortuosum / kanna leaves and aerial parts Not applicable Not applicable · vs Not applicable	Mesembrine C17H23NO3 (CID 394162); mesembrenone C17H21NO3 (CID 216272); hordenine C10H15NO (CID 68313). Checked through the PubChem API 2026-10-25. n/a Methods, limits and funding Outcomes: Uses, safety, interactions Limitations: Database records. Read: full-text
Reay 2020 Sceletium tortuosum (Zembrin) ameliorates experimentally induced anxiety in healthy volunteers. Hum Psychopharmacol · PMID 32761980 · DOI	Controlled trial	20 20 young healthy volunteers in two small placebo-controlled studies	Zembrin standardized S. tortuosum extract aerial parts 25 mg single dose Single dose · vs Placebo	Study 1 (multitasking stress): no treatment effect. Study 2 (public-speaking task): lower subjective anxiety before the stress and a treatment-by-time effect on heart rate in the Zembrin group. Study 1 null; study 2 lower pre-stress anxiety (statistics not in the abstract) Methods, limits and funding Outcomes: Subjective mood/anxiety, heart rate, skin conductance under laboratory stress Limitations: Only 20 people across two studies, single dose, laboratory stress in healthy young people, authors call the evidence tentative. A co-author (Badmaev) is also on a trial affiliated with the extract's marketers. Funding and conflicts: Not stated in the abstract record; co-author affiliation American Medical Holdings Inc. Read: abstract
Shikanga 2012 In vitro permeation of mesembrine alkaloids from Sceletium tortuosum across porcine buccal, sublingual, and intestinal mucosa. Planta Med · PMID 22105579 · DOI	Laboratory research in-vitro	Pig intestinal, sublingual and buccal tissue	Pure mesembrine alkaloids and three crude S. tortuosum extracts aerial parts Not applicable (laboratory) Not applicable · vs Caffeine and atenolol reference compounds	Mesembrine crossed intestinal tissue faster than caffeine; mesembranol similar to caffeine; mesembrenol and mesembrenone lower than caffeine but higher than a poorly absorbed reference; mouth tissues were less permeable than intestine but may contribute when the material is chewed for a long time. Qualitative Methods, limits and funding Outcomes: Alkaloid permeability across tissue Limitations: Pig tissue in a dish; not human absorption. Funding and conflicts: Not stated in the abstract record. Read: abstract
Terburg 2013 Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala and its connection to the hypothalamus. Neuropsychopharmacology · PMID 23903032 · DOI	Controlled trial	16 16 healthy adults, double-blind placebo-controlled crossover with fMRI	Zembrin standardized S. tortuosum extract aerial parts 25 mg single dose Single dose per session · vs Placebo	Amygdala reactivity to fearful faces (low perceptual load) was lower after Zembrin; amygdala-hypothalamus coupling was also reduced. Reduced amygdala reactivity (statistic not in the abstract) Methods, limits and funding Outcomes: Amygdala reactivity to fearful faces; amygdala-hypothalamus coupling Limitations: Very small, single dose, brain-imaging outcome in healthy people; not a symptom outcome. Co-author N. Gericke is linked to the extract maker in other papers read. Funding and conflicts: Funding and conflicts not stated in the abstract record. Read: abstract
WebMD 2026 Sceletium: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing WebMD · Source	Authoritative guidance	General readers	Sceletium tortuosum / kanna leaves and aerial parts Not applicable Not applicable · vs Not applicable	Benefits are not well defined; common side effects are headache and upset stomach; serious allergic reactions are possible; FDA has not reviewed it for safety and effectiveness; some supplements contained other ingredients such as ephedrine; discuss MAOIs (within two weeks), SSRIs, SNRIs, tricyclics, antipsychotics, triptans and St. John's wort with a provider; interactions are not fully understood; not enough research on alcohol; pregnancy and breastfeeding effects are not known; tell a provider about kidney or liver problems, mental health problems, past suicide attempt, psychosis or substance misuse. n/a Methods, limits and funding Outcomes: Uses, safety, interactions Limitations: Consumer reference page that cites a small set of the same studies; not a primary source. Page text read 2026-10-25. Read: full-text
de Jong 2026 Mesembryanthemum tortuosum and Zembrin: Mixed Evidence from In vivo Animal and Clinical Studies on their Antidepressant and Anxiolytic Effects. Planta Med · PMID 41771298 · DOI	Systematic review	Published animal and human studies of M. tortuosum, Zembrin and mesembrine alkaloids up to July 2025	M. tortuosum products, mostly the Zembrin extract aerial parts Not given in the abstract Varies by study · vs Placebo or other (not given in the abstract)	Authors found a favourable safety profile and possible anxiety, cognition, stress-resilience and mood effects, but not all studies showed benefit; small samples; clinically irrelevant populations; some outcomes limited to EEG or reaction time. Mixed Methods, limits and funding Outcomes: Safety and anxiolytic/antidepressant effects Limitations: Abstract only; review of small studies; no pooled numbers in the abstract. Funding and conflicts: No conflicts of interest declared (abstract record). Read: abstract

What we do not know yet

No trial of kanna in people with depression or an anxiety disorder was found.
All human trials found used one branded extract and most involve authors linked to its maker.
No trial longer than 3 months; no sleep trial; no independent large trial.
No study or case report of kanna with SSRIs, MAOIs, triptans, alcohol or PDE4 medicines, so the serotonin-syndrome risk is theoretical.
No human data in pregnancy, breastfeeding or children.
EMA and NCCIH have no kanna page that could be found; South African drug scheduling was not found.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue. A person reads each one before it changes any rating or safety wording.

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 8

▼

Amygdala response to fearful faces (fMRI)

Lowered in trials

How strongly a brain region involved in reacting to threat lights up on a scan when a person sees fearful faces.

Very low certainty

Results and what it means

Why it was measured

Used as a laboratory marker for anxiety-related brain activity.

Statistical vs. clinical meaning

A brain-scan marker; it does not show less anxiety in daily life.

Safety implication

None reported in the abstract.

Study	Result	People	Product
¹⁹	Amygdala reactivity to fearful faces (low perceptual load) was lower after one dose of Zembrin than placebo; amygdala-hypothalamus coupling was also reduced.	16 healthy adults, crossover	Zembrin single dose vs placebo

¹⁹

↕

Self-reported anxiety under laboratory stress

Mixed results in trials

How anxious volunteers say they feel before and during a stressful task.

Very low certainty

Results and what it means

Why it was measured

Main outcome of the two small laboratory studies.

Statistical vs. clinical meaning

One of two studies positive, on one time point; small.

Safety implication

None.

Study	Result	People	Product
¹⁷	Study 1 (multitasking): no treatment effect. Study 2 (public speaking): significantly lower anxiety at the pre-stress point in the Zembrin group.	20 healthy young adults in two studies	Zembrin single dose vs placebo

¹⁷

↕

Heart rate during laboratory stress

Mixed results in trials

Pulse measured during a simulated speech task.

Very low certainty

Results and what it means

Why it was measured

A physical sign of the stress response.

Statistical vs. clinical meaning

The direction and size of the change are not given in the abstract.

Safety implication

Kanna might affect heart rate; this is not established.

Study	Result	People	Product
¹⁷	A significant treatment-by-time interaction on heart rate was reported in study 2; the abstract gives no values.	Healthy young adults	Zembrin single dose vs placebo

¹⁷

▲

Cognitive flexibility and executive function scores

Raised in trials

Computerised test scores (CNS Vital Signs) that measure how easily a person switches tasks and plans.

Very low certainty

Results and what it means

Why it was measured

Primary outcomes of the 3-week crossover trial.

Statistical vs. clinical meaning

Statistically significant in a small trial with several outcomes; clinical meaning unknown.

Safety implication

None reported.

Study	Result	People	Product
⁴	Cognitive set flexibility improved (P < 0.032) and executive function improved (P < 0.022) versus placebo.	21 healthy adults, mean age 54.6	Zembrin 3 weeks vs placebo, crossover

⁴

↕

Depression rating scale in healthy adults (HAM-D)

Mixed results in trials

A clinician-rated scale of depression symptoms.

Not enough evidence

Results and what it means

Why it was measured

Recorded as a safety and mood check in the cognition trial.

Statistical vs. clinical meaning

People with no depression cannot show an antidepressant effect.

Safety implication

None.

Study	Result	People	Product
⁴	The abstract reports 'positive changes in mood and sleep' without numbers.	Healthy adults with no depression	Zembrin 3 weeks

⁴

▲

Complex reactive agility and visual tracking

Raised in trials

Test performance when a person must respond to repeated visual cues while also doing a thinking task.

Very low certainty

Results and what it means

Why it was measured

Primary outcome of the 8-day trial.

Statistical vs. clinical meaning

A single small trial; the practical size of the gain is unknown.

Safety implication

None reported.

Study	Result	People	Product
⁷	Significant improvements in complex reactive performance with a cognitive load versus placebo; no difference in simple reaction tests.	60 recreationally trained adults aged 20-35	S. tortuosum extract 8 days vs placebo

⁷

●

Total mood score (Profile of Mood States)

No clear change in trials

A questionnaire total of tension, depression, anger, vigour, fatigue and confusion.

Very low certainty

Results and what it means

Why it was measured

Checked for any mood effect in young trained adults.

Statistical vs. clinical meaning

A null result for mood in healthy young adults.

Safety implication

None.

Study	Result	People	Product
⁷	No significant difference between the extract and placebo in total mood score or in the alertness/energy scale.	60 trained adults	S. tortuosum extract 8 days

⁷

●

Vital signs, ECG, blood and urine tests over 3 months

No clear change in trials

Standard safety checks: blood pressure and pulse, heart tracing, blood counts, blood chemistry and urine tests.

Low certainty

Results and what it means

Why it was measured

Primary outcome of the 3-month safety trial.

Statistical vs. clinical meaning

Reassuring but small: 37 healthy adults for 3 months cannot rule out rarer problems or interactions.

Safety implication

Does not cover people taking other medicines or with existing illness.

Study	Result	People	Product
¹³	No apparent differences between two extract amounts and placebo in vital signs, ECG, weight or physical examination, and no significant changes in haematology or biochemistry.	37 healthy adults, 12-13 per group	Zembrin standardized extract once daily for 3 months vs placebo

¹³

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

Antidepressants and other serotonin-acting medicines: the main concern. Kanna extract blocks the serotonin transporter in lab tests, the same target as SSRI antidepressants. A consumer drug reference says to discuss MAOIs (within the past two weeks), SSRIs, SNRIs, tricyclic antidepressants, antipsychotics, triptans for migraine and St. John's wort with a provider first, and says interactions are not fully understood. No trial or case report of kanna combined with these medicines was found. The risk of too much serotonin (serotonin syndrome) is therefore a reasoned worry from the mechanism, not a documented event. Do not combine without a doctor or pharmacist. Pharmacological theory ^{6 8 20}
Not a treatment for depression or anxiety. No trial has tested kanna in people with depression or an anxiety disorder. Do not stop or replace prescribed treatment with it. Authoritative guidance ^{14 21}
Pregnancy, breastfeeding and children: unknown, so avoid. No source read gives human safety data. A drug reference states it is not known whether kanna affects pregnancy or passes into breast milk. Traditional practice includes giving children and infants kanna, but that is a record of practice and not evidence of safety. Authoritative guidance ^{20 2}
Products may contain other ingredients. Kanna supplements have been found to contain ephedrine (a banned stimulant) and varying amounts of hordenine, a stimulant-like plant compound. Content differs widely between products and batches. Laboratory ^{9 1 15 20}
Only short human studies exist. The longest human trial found lasted 3 months in 37 healthy adults and found no safety signal. Long-term use, use in people with illness, and use with other medicines have not been studied. Controlled trial ^{13 21}
Alcohol, sedatives, cannabis and other psychoactive substances. There is not enough research to know whether kanna interacts with alcohol. Kanna was traditionally used as a sedative and to cause intoxication, and a US military guidance page warns about use together with cannabis or other psychoactive agents. Vaping or snorting kanna products has not been studied. Authoritative guidance ^{20 15 2}
Mental health history. A drug reference advises telling a provider about depression, a past suicide attempt, anxiety, hallucinations, paranoia or psychosis, and about a history of misusing medicines or drugs, before using kanna. Authoritative guidance ²⁰

Side effects 6

Effect	How often	Severity and recovery	Evidence
Headache Healthy adults, 37 people; also listed by a consumer drug reference.	In the 3-month trial, headache was the most common adverse event but was more frequent in the placebo groups than in the extract groups (counts not in the abstract).	mild Not stated	Controlled trial ^{13 20}
Upset stomach or abdominal pain The drug reference lists upset stomach as a common side effect.	Abdominal pain was the second most reported event in the 3-month trial, more often with placebo than with the extract.	mild Not stated	Controlled trial ^{13 20}
Fatigue, drowsiness, difficulty concentrating Reported in a US military guidance page summarising supplement studies; numbers not given.	Not established	mild to moderate Not stated	Authoritative guidance ¹⁵
Serious allergic reaction (breathing trouble, swelling of face or throat, hives, fainting) Listed as possible; no frequency given.	Not established	serious Not stated	Authoritative guidance ²⁰
Psychiatric or neurological effects with overdose or unstandardised products A review of 15 herbal aphrodisiacs including kanna reports such effects across the group; the abstract does not split out kanna.	Not established	mild to severe Not stated	Systematic review ³
Harm from adulterants such as ephedrine Ephedrine alkaloids pose serious health risks, including death, according to the military guidance page; this is about the adulterant, not kanna itself.	Not established	potentially serious Not stated	Laboratory ^{9 15}

Liver

No LiverTox entry for kanna or Sceletium was found (NCBI Bookshelf search, 2026-10-25). In a 3-month trial of 37 healthy adults, blood chemistry showed no significant change, and a 90-day rat study found no treatment-related effects; neither abstract names liver tests specifically. A drug reference advises telling a provider about kidney or liver problems. ^{13 11 20}

How often. No frequency data and no human case reports of liver injury were found.

Monitoring. No agency monitoring advice found. People with liver or kidney disease should ask a doctor first.

This is a safety connection. It is not evidence that Kanna (Sceletium tortuosum) supports liver health.

Medicines and supplements 9

With	Why it matters	Importance	Evidence	What to do
SSRI and SNRI antidepressants (e.g. fluoxetine, paroxetine, sertraline, duloxetine, venlafaxine) antidepressant	Kanna alkaloids block the serotonin transporter in lab tests (mesembrine Ki 1.4 nM; extract IC50 4.3 ug/mL), the same target as these medicines.	No trial or case report was found. A drug reference lists these medicines to discuss first. Added serotonin effects (including serotonin syndrome) are plausible from the mechanism but not documented.	Pharmacological theory Not enough evidence ^{6 8 20}	Do not combine without a doctor or pharmacist.
MAOI antidepressants and Parkinson's medicines (monoamine oxidase inhibitors) antidepressant	Both raise brain serotonin through different routes; one in-vitro study of a high-mesembrine extract described it as also releasing monoamines.	The drug reference says to discuss any MAOI used within the past two weeks. No human data.	Authoritative guidance Not enough evidence ^{20 2}	Do not combine; ask a doctor about timing.
Tricyclic antidepressants (amitriptyline, nortriptyline and others) antidepressant	Overlapping serotonin action.	Listed by the drug reference as a medicine to discuss, even when used for something other than depression.	Authoritative guidance Not enough evidence ²⁰	Ask a pharmacist first.
Triptans for migraine (sumatriptan, eletriptan and others) migraine medicine	Triptans act on serotonin receptors; overlap with kanna's serotonin action is a concern.	Listed by the drug reference. No human data.	Authoritative guidance Not enough evidence ²⁰	Ask a pharmacist first.
Antipsychotic medicines psychiatric medicine	Not explained in the sources.	Listed by the drug reference to discuss first. No human data.	Authoritative guidance Not enough evidence ²⁰	Ask the prescriber first.
St. John's wort and other serotonin-acting supplements herb	Overlapping serotonin effects.	St. John's wort is named by the drug reference. Other herbs were not discussed in the sources.	Authoritative guidance Not enough evidence ²⁰	Do not combine without advice.
Drugs that block PDE4 (for example some asthma, COPD and psoriasis medicines) respiratory/skin medicine	The extract and mesembrenone block PDE4 in lab tests; no source tested a combination.	Reasoned from the mechanism only; no source read raises it.	Pharmacological theory Not enough evidence ^{6 8}	Ask a pharmacist if you take such a medicine.
Alcohol, sedatives, sleep aids and cannabis central nervous system	Traditional sedative and intoxicating use; interaction not studied.	The drug reference says there is not enough research to know about alcohol; a military guidance page raises concern about use with cannabis.	Authoritative guidance Not enough evidence ^{20 15 2}	Avoid combining until more is known.
Liver-enzyme (CYP) drugs metabolism	Mesembrine alkaloids are broken down in the liver by several steps; which enzymes are involved and whether kanna changes other drugs' levels was not found.	No data.	Animal research Not enough evidence ¹⁰	Tell your pharmacist you take kanna.

Who should check first 8

Situation	Advice	Evidence
People taking antidepressants, MAOIs, triptans, antipsychotics or St. John's wort	Avoid unless a doctor agrees. See interactions.	Authoritative guidance ²⁰
Allergy to kanna, kougoed, channa or Sceletium	Do not use.	Authoritative guidance ²⁰
Pregnancy and breastfeeding	Avoid; effects are unknown.	Authoritative guidance ²⁰
Children and infants	No safety data in any source read. Do not use because of traditional practice.	Traditional use ²
Psychosis, paranoia, hallucinations, past suicide attempt or severe depression or anxiety	Talk to a doctor first.	Authoritative guidance ²⁰
History of misusing medicines or drugs	Talk to a doctor first.	Authoritative guidance ²⁰
Kidney or liver disease	Tell your provider first.	Authoritative guidance ²⁰
Drug testing at work, sport or military	The main alkaloids are broken down into metabolites that could be detected in a urine screen (rat and liver-prep study); US military policies bar substances taken to alter the state of mind.	Animal research ^{10 15}

Overdose, product quality and regulators

Summary. Rat studies of the Zembrin extract found no harm at the highest amounts tested. Human overdose information was not found; the drug reference says to contact Poison Control or emergency services if too much is used.

Animal. In Wistar rats, a 14-day study up to 5000 mg/kg/day and a 90-day study up to 600 mg/kg/day produced no deaths or treatment-related effects; these were the highest amounts tested.

Human doses studied. Not given here. Trial amounts apply to one branded extract and are not a safe-use guide.

High dose or long term signals. Not studied in people beyond 3 months.

Overdose response. No human overdose data found. A drug reference says to get medical help immediately after taking too much.

Genotoxicity. Not stated in the abstract read.

Toxic plant parts. The leaves and aerial parts are used. Safety of roots or other parts was not found.

Content varies between products and batches, and supplement adulteration has been found.

Ephedrine adulteration. Ephedrine, a stimulant banned in herbal products and supplements, was confirmed in one commercial kanna sample by mass spectrometry. The abstract does not give how many products were tested. ^{9 20 15}

Hordenine. Hordenine, a stimulant-like plant compound found naturally in kanna, ranged from 0.027 to 1.07 mg per gram across six commercial products. A military guidance page says products have been reported adulterated with hordenine and ephedrine, both on its prohibited list. ^{1 15}

Plant and batch variation. The amount of each chemical changes with growing area, weather, harvest time and processing, so a new brand or bottle may act differently. Whether fermentation raises potency is unsettled. ^{20 2}

Body	Action	Date
US FDA (United States)	A drug reference says the FDA has not reviewed kanna for safety and effectiveness and has not approved it; supplements cannot be marketed to treat or cure a disease. A 2021 review describes it as sold as a dietary supplement and food ingredient in the USA. source
US Department of Defense (Operation Supplement Safety) (United States)	Kanna is not on the DoD Prohibited Dietary Supplement Ingredients List (content current to 15 December 2025), but service policies bar substances used to alter the state of mind, and products may be adulterated with prohibited ingredients. source	2025-12-15
South African law (South Africa)	The plant is native to South Africa. The 2021 review says sceletium is regulated as a food there, and that access and use of indigenous plants fall under the biodiversity law (NEMBA) and its bioprospecting benefit-sharing rules. Whether it is scheduled as a drug in South Africa was not found. source

When to get medical help

Agitation, confusion, sweating, shivering, muscle twitching or stiffness, fast heartbeat, diarrhoea or fever after taking kanna with an antidepressant or other serotonin medicine: these are general warning signs of serotonin syndrome, not signs described in kanna reports. Seek urgent care.
Swelling of the face, lips or throat, trouble breathing, hives or fainting.
Hallucinations, paranoia, thoughts of self-harm or sudden severe change in mood.
Chest pain, a very fast or irregular heartbeat (especially if the product might contain ephedrine).
Taking much more than intended: contact Poison Control or emergency services (a drug reference says to do this).

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 kanna?

Kanna is a succulent plant from South Africa, also called Sceletium or kougoed. Its dried or fermented leaves and stems were chewed, smoked or made into tea or tincture for mood, relaxation and pain. Today it is sold as powders, capsules, vapes and gummies. It is a psychoactive plant, not a proven treatment.

^{2 20}

Does kanna work for anxiety or depression?

Not shown. Two tiny studies of 20 healthy volunteers gave mixed results on laboratory anxiety, and no trial has tested kanna in people with depression or an anxiety disorder. A 2026 review calls the evidence mixed. Do not replace prescribed treatment with it.

^{17 14 21}

Can I take kanna with an SSRI or other antidepressant?

Ask a doctor or pharmacist first. Kanna blocks the serotonin transporter in lab tests, like SSRIs. A drug reference lists SSRIs, SNRIs, tricyclics, MAOIs, triptans, antipsychotics and St. John's wort as medicines to discuss first. No study or case report tested the combination, so the risk of too much serotonin is a reasoned concern rather than a documented event.

^{6 8 20}

Is kanna safe with MAOIs?

A drug reference says to discuss any MAOI taken within the past two weeks. There is no human data on the combination, so the safe course is to avoid it unless a doctor agrees.

^{20 2}

What does PDE4 inhibition mean for medicines?

The extract and one of its alkaloids block the enzyme PDE4 in lab tests. Some medicines for lung and skin conditions also block PDE4. No source tested kanna with them, so this is only a possible overlap; ask a pharmacist if you take one.

^{6 8}

What are the side effects?

Headache and upset stomach are listed by a drug reference. In a 3-month trial of 37 healthy adults headache and stomach pain were reported, but more often in the placebo groups. A military guidance page lists fatigue, drowsiness and trouble concentrating, and serious allergic reactions are possible.

^{13 20 15}

Is kanna safe in pregnancy or when breastfeeding?

Its effects are unknown. A drug reference states it is not known whether kanna affects pregnancy or passes into breast milk, so avoiding it is the cautious choice. Traditional use for babies is not evidence of safety.

^{20 2}

Can I drink alcohol or use sedatives or cannabis with kanna?

Not enough research exists to know. Kanna was traditionally used as a sedative and to cause intoxication, and a US military guidance page warns about combining it with cannabis or other psychoactive agents. Ask a doctor.

^{20 15 2}

Is kanna legal?

It depends on the country. The plant is native to South Africa, where a 2021 review says it is regulated as a food. The same review reports no legal products on the European market, no listing in Australia's ingredient lists, eleven licences in Canada (as of August 2020), and a ban on mesembrine in Russia. The US FDA has not approved it. Rules may have changed, so check local law.

^{2 20}

Are kanna products pure?

Not always. Ephedrine, a banned stimulant, was found in one commercial kanna sample, and hordenine content varied about 40-fold across six products. A military guidance page says products have been reported adulterated with hordenine and ephedrine. Independent lab testing is the only way to know what is inside.

^{9 1 15}

Can kanna make me fail a drug test?

It might. The main alkaloids are broken down into metabolites that, in a rat and human liver study, could be detected in urine screens. US military policy bars substances taken to alter the state of mind. Check the rules that apply to you.

^{10 15}

How long has kanna been studied for safety?

The longest human trial lasted 3 months in 37 healthy adults and found no safety signal. A 90-day rat study at high amounts also found none. Long-term safety, use alongside medicines, and use in ill people have not been studied. Ask a doctor or pharmacist about amounts.

^{13 11}

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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 abstract of every PubMed study cited, read the full text of a 2021 regulatory review (Brendler), the WebMD and Operation Supplement Safety pages, and checked plant names in GBIF and NCBI Taxonomy and compound records in PubChem. EMA and NCCIH were checked and no kanna page was found.
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. Most human trials of kanna include authors linked to the maker of the Zembrin extract or its marketers; this is flagged in each study record.

Sources 21

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

Appley MG, Chambers MI, Musah RA. Quantification of hordenine in a complex plant matrix by direct analysis in real time-high-resolution mass spectrometry: Application to the 'plant of concern' Sceletium tortuosum.. Drug Test Anal. 2022. PMID 34750996. DOI 10.1002/dta.3193. (abstract)
Brendler T, Brinckmann JA, Feiter U, et al.. Sceletium for Managing Anxiety, Depression and Cognitive Impairment: A Traditional Herbal Medicine in Modern-Day Regulatory Systems.. Curr Neuropharmacol. 2021. PMID 33588735. DOI 10.2174/1570159X19666210215124737. (full-text)
Brunetti P, Lo Faro AF, Tini A, et al.. Pharmacology of Herbal Sexual Enhancers: A Review of Psychiatric and Neurological Adverse Effects.. Pharmaceuticals (Basel). 2020. PMID 33066617. DOI 10.3390/ph13100309. (abstract)
Chiu S, Gericke N, Farina-Woodbury M, et al.. Proof-of-Concept Randomized Controlled Study of Cognition Effects of the Proprietary Extract Sceletium tortuosum (Zembrin) Targeting Phosphodiesterase-4 in Cognitively Healthy Subjects: Implications for Alzheimer's Dementia.. Evid Based Complement Alternat Med. 2014. PMID 25389443. DOI 10.1155/2014/682014. (abstract)
GBIF. GBIF Backbone Taxonomy: Mesembryanthemum tortuosum L.. GBIF. 2026. (full-text)
Harvey AL, Young LC, Viljoen AM, et al.. Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids.. J Ethnopharmacol. 2011. PMID 21798331. DOI 10.1016/j.jep.2011.07.035. (abstract)
Hoffman JR, Markus I, Dubnov-Raz G, et al.. Ergogenic Effects of 8 Days of Sceletium Tortuosum Supplementation on Mood, Visual Tracking, and Reaction in Recreationally Trained Men and Women.. J Strength Cond Res. 2020. PMID 32740286. DOI 10.1519/JSC.0000000000003693. (abstract)
Krstenansky JL. Mesembrine alkaloids: Review of their occurrence, chemistry, and pharmacology.. J Ethnopharmacol. 2017. PMID 27939420. DOI 10.1016/j.jep.2016.12.004. (abstract)
Lesiak AD, Cody RB, Ubukata M, et al.. Direct analysis in real time high resolution mass spectrometry as a tool for rapid characterization of mind-altering plant materials and revelation of supplement adulteration - The case of Kanna.. Forensic Sci Int. 2016. PMID 26821203. DOI 10.1016/j.forsciint.2015.12.037. (abstract)
Meyer GM, Wink CS, Zapp J, et al.. GC-MS, LC-MS(n), LC-high resolution-MS(n), and NMR studies on the metabolism and toxicological detection of mesembrine and mesembrenone, the main alkaloids of the legal high 'Kanna' isolated from Sceletium tortuosum.. Anal Bioanal Chem. 2015. PMID 25240931. DOI 10.1007/s00216-014-8109-9. (abstract)
Murbach TS, Hirka G, Szakonyine IP, et al.. A toxicological safety assessment of a standardized extract of Sceletium tortuosum (Zembrin) in rats.. Food Chem Toxicol. 2014. PMID 25301237. DOI 10.1016/j.fct.2014.09.017. (abstract)
NCBI Taxonomy. NCBI Taxonomy: Mesembryanthemum tortuosum (taxid 216016). NCBI Taxonomy. 2026. (full-text)
Nell H, Siebert M, Chellan P, et al.. A randomized, double-blind, parallel-group, placebo-controlled trial of Extract Sceletium tortuosum (Zembrin) in healthy adults.. J Altern Complement Med. 2013. PMID 23441963. DOI 10.1089/acm.2012.0185. (abstract)
Olatunji TL, Siebert F, Adetunji AE, et al.. Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological and clinical activities.. J Ethnopharmacol. 2021. PMID 34333104. DOI 10.1016/j.jep.2021.114476. (abstract)
Operation Supplement Safety (US Department of Defense / Uniformed Services University). Kanna: Uses and Safety in Dietary Supplements. Operation Supplement Safety (US Department of Defense / Uniformed Services University). 2025. (full-text)
PubChem. PubChem records: mesembrine (CID 394162), mesembrenone (CID 216272), hordenine (CID 68313). PubChem. 2026. (full-text)
Reay J, Wetherell MA, Morton E, et al.. Sceletium tortuosum (Zembrin) ameliorates experimentally induced anxiety in healthy volunteers.. Hum Psychopharmacol. 2020. PMID 32761980. DOI 10.1002/hup.2753. (abstract)
Shikanga EA, Hamman JH, Chen W, et al.. In vitro permeation of mesembrine alkaloids from Sceletium tortuosum across porcine buccal, sublingual, and intestinal mucosa.. Planta Med. 2012. PMID 22105579. DOI 10.1055/s-0031-1280367. (abstract)
Terburg D, Syal S, Rosenberger LA, et al.. Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala and its connection to the hypothalamus.. Neuropsychopharmacology. 2013. PMID 23903032. DOI 10.1038/npp.2013.183. (abstract)
WebMD. Sceletium: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing. WebMD. 2026. (full-text)
de Jong M, van Niekerk S, Hamman J, et al.. Mesembryanthemum tortuosum and Zembrin: Mixed Evidence from In vivo Animal and Clinical Studies on their Antidepressant and Anxiolytic Effects.. Planta Med. 2026. PMID 41771298. DOI 10.1055/a-2809-5144. (abstract)

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.