Herbs & Botanicals · Root-beer tree with a cancer warning
Sassafras
Sassafras albidum · also called Ague tree, cinnamonwood, saloop; leaf powder is filé
Sassafras is an eastern US tree. Its root bark once flavoured root beer and tea, and its leaves are ground into filé powder for gumbo. No human study shows it treats anything. The key caution: the root bark and its oil contain safrole, which caused liver cancer in rodents, and the US bans them as food additives.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Sassafras
Sassafras (Sassafras albidum) is best known for what it should not be used for. Its root bark and oil are rich in safrole, which caused liver cancer in rodents. The US has banned oil of sassafras and sassafras tea as food since 1960. No human trial shows any benefit. The leaf, sold as filé, is a different product, and a small 1997 test found most leaf samples had safrole below detection.
Root bark, oil and leaf are different
In a small 1997 FDA test of 26 products, most leaf samples had no detectable safrole, while one oil held up to 92.4 percent and brewed root bark teas held 0.09 to 4.66 mg per cup.
The US allows a root bark extract as a flavouring only if it is safrole-free. We could not check retail safrole-free claims.
What the rules say
A 1960 order treats food with added safrole or oil of sassafras, and sassafras bark meant to flavour another food such as tea, as adulterated. The rule text does not mention leaves.
At a glance
Traditional uses history, not proof
- Root bark infusions for fevers, diarrhea and rheumatism by Native Americans (MSK).
- Root beer flavouring and perfume scent (MSK).
- Filé powder from the leaves as a gumbo thickener.
Studied for research
- Detox, inflammation, arthritis: insufficient (traditional claims only)
- Cancer cells and blood sugar: insufficient (lab and animal only)
Main compounds
- Safrole, the main oil, a rodent liver carcinogen
- Isosafrole and related compounds
- Lignans (not described in sources read)
Common forms
- Root bark tea
- Oil of sassafras
- Leaf powder (filé)
Research links: 21 CFR 189.180: Safrole (eCFR) · 21 CFR 172.580: Safrole-free extract of sassafras · MSK: Sassafras · Safrole in sassafras products (PubMed) · Research Library · Genes & Biomarkers Library
The plant and its history
- Accepted scientific name
- Sassafras albidum
- Naming authority
- (Nutt.) Nees
- Common names
- Sassafras (English); Ague tree (English); Cinnamonwood (English); Saloop (English)
- Botanical family
- Lauraceae
- Classification
- Plantae > Laurales > Lauraceae > Sassafras > Sassafras albidum
- Native range
- Eastern United States (MSK).
- Habitat
- Not checked.
- What the plant looks like
- Roots: Root bark is the safrole-rich part.; Leaves: Leaves are ground into filé.; Stems: Not checked.; Flowers: Not checked.; Fruit: Not checked.
- Cultivation
- Not checked.
- Harvest and processing
- Root bark is dried and used for teas, extracts and oil; leaves are dried and ground for filé.
- Look-alikes and adulterants
- Name: Other Sassafras species (S. tzumu in China, S. randaiense in Taiwan); Note: A 2023 review says the genus has three species, in eastern North America and East Asia. Whether their chemistry matches S. albidum was not checked.
- Sustainability and conservation
- Not checked.
The plant and the parts used
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Native American and later folk use, eastern North America | Root bark infusions for fevers, diarrhea and rheumatism; also used to scent perfume and to flavour root beer. | s-msk-sassafras |
| US regulation | Safrole and oil of sassafras banned as food additives by a December 1960 order. | s-cfr-189-180 |
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 |
|---|---|---|---|---|
| Safrole PubChem 5144 | phenylpropene | Root bark and oil Oil of sassafras is about 80 percent safrole (21 CFR 189.180); one oil tested at 92.4 percent (1997). | Liver tumours in rodents; cell-death effects in cancer cell lines (lab). 9 1 6 7 | Authoritative guidance |
| Isosafrole PubChem 637796 | phenylpropene | Derivative of safrole Not given. | Named with safrole in the US food rule. 9 7 | Authoritative guidance |
| Lignans | lignan | Not specified Not given. | Not described in the sources read; no lignan data were opened this round. | Insufficient |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Metabolic activation by liver enzymes (CYP3A4) | CYP3A4 | A 2026 lab and computer study found safrole is less efficiently activated than methyleugenol; both are hepatotoxic flavourings (IARC 2B vs 2A). 11 | Laboratory research |
| Cancer cell death pathways | Caspases, mitochondria | Safrole caused apoptosis in cancer cell lines (MSK). 5 | Laboratory research |
| Liver drug enzymes | CYP1A2, CYP2A6, CYP2E1 | Safrole inhibited these human enzymes in vitro. 5 | Laboratory research |
Absorption, metabolism and elimination
- Absorption
- Not covered in the sources read.
- Distribution
- Not covered.
- Metabolism
- Activated mainly by liver cytochrome P450 enzymes including CYP3A4 (lab).
- Elimination
- Not covered.
- Bioavailability
- Not established in people.
Isolated compounds versus whole extracts
The cancer and liver findings are for isolated safrole or oil; the whole plant varies. Leaf has far less safrole than root bark or oil in a small 1997 test.
Nutritional composition
Sassafras is not a nutrient. Filé powder is a cooking thickener; root bark is not allowed as a food flavouring unless safrole-free.
7 not enough evidence
What is Sassafras good for?
The uses people ask about and how strong the human evidence is for each. None is proven, and the safety section matters more than any benefit.
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.
'Detox' and cleansing
Not enough evidenceSassafras root bark tea has been promoted as a 'detox' or spring blood cleanser. No human study shows it does this.
1 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
No human trial was found for this use. MSK says studies of sassafras are limited and only in vitro or in animals.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Traditional claim only; no human data in the sources read.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
Source is a monograph, not a trial search of all literature.
Why researchers looked
MSK lists detoxification as a purported use of sassafras.
Traditional use
Root bark teas were a traditional spring tonic in eastern North America (MSK mentions fevers, diarrhea and rheumatism as traditional uses).
Proposed mechanism Pharmacological theory
No mechanism supports a detox effect. The best-known action of safrole is toxic to the liver in rodents.
A proposed mechanism does not show that the effect happens in people.
Root bark and its oil contain safrole, which caused liver tumours in rodents. Because of this, the US treats sassafras tea and oil of sassafras in food as adulterated.
Inflammation and arthritis
Not enough evidenceSassafras has been used for joint pain and arthritis in folk medicine. No human evidence supports it.
2 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
No human trial of sassafras for arthritis or inflammation was found.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Traditional use plus group-level lab data only.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
The 2026 review is about a chemical family, not sassafras.
Why researchers looked
MSK lists inflammation and arthritis as purported uses.
Traditional use
Traditionally used for rheumatism.
Proposed mechanism Laboratory research
A 2026 review says phenylpropenes as a group, which includes safrole, have shown anti-inflammatory effects in lab and animal studies. This is not specific to sassafras products.
A proposed mechanism does not show that the effect happens in people.
Root bark and its oil contain safrole, which caused liver tumours in rodents. Because of this, the US treats sassafras tea and oil of sassafras in food as adulterated.
Fever and diarrhea (traditional)
Not enough evidenceNative American and later folk use of sassafras root bark infusions for fever and diarrhea. Not tested in people.
1 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
No human trial was found.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Historical use is not proof.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
Based on one monograph's statement.
Why researchers looked
Named in the MSK monograph as traditional use.
Traditional use
Infusions of root bark were used for fevers, diarrhea and rheumatism.
Proposed mechanism Pharmacological theory
None established.
A proposed mechanism does not show that the effect happens in people.
Root bark and its oil contain safrole, which caused liver tumours in rodents. Because of this, the US treats sassafras tea and oil of sassafras in food as adulterated.
Anti-cancer effects in cells and mice
Not enough evidenceSafrole killed some human cancer cell lines in the lab and affected leukemia cells in mice. This is not a treatment, and safrole itself is a rodent liver carcinogen.
2 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
Lab and animal only. MSK states these findings do not offset the carcinogen concern.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Cell and mouse findings rarely carry over to people, and the compound is itself carcinogenic in animals.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
Papers cited by MSK were not opened.
Why researchers looked
Safrole was tested on cancer cell lines (tongue, leukemia, oral, prostate) in the papers cited by MSK.
Traditional use
None.
Proposed mechanism Laboratory research
MSK describes cell-death pathways (mitochondria, caspases, endoplasmic reticulum stress) in cell lines and effects on leukemia cells in mice.
A proposed mechanism does not show that the effect happens in people.
Do not use sassafras to try to treat cancer. Safrole is listed as reasonably anticipated to be a human carcinogen.
Blood sugar (rodent studies)
Not enough evidenceOne rodent study cited by MSK reported effects of safrole on blood sugar and fats. No human study.
2 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
No human study.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
One animal-study reference seen only in MSK's list; the 2026 review also lists antidiabetic effects for phenylpropenes in preclinical work.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
Not opened; the 2026 review is about a chemical family.
Why researchers looked
MSK cites a 2013 study of safrole in rodents and cells.
Traditional use
None.
Proposed mechanism Animal research
Not established.
A proposed mechanism does not show that the effect happens in people.
Safrole, not the whole plant, was tested.
Flavour and root beer
Not enough evidenceSassafras root bark was used to flavour root beer and to scent perfume. That was a flavour use, not a health benefit, and the safrole concern ended it in US food.
3 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
Not a health claim.
Results
Not applicable.
Effect sizes as reported
None available.
Why this rating
No health outcome studied.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
A US safrole-free root bark extract is allowed as a food flavouring (21 CFR 172.580); retail claims of 'safrole-free' were not checked.
Why researchers looked
Historic flavouring use.
Traditional use
MSK notes root bark was used to flavour root beer. US law has treated safrole and oil of sassafras as banned food additives since 1960.
Proposed mechanism Authoritative guidance
Not applicable.
A proposed mechanism does not show that the effect happens in people.
Root bark and its oil contain safrole, which caused liver tumours in rodents. Because of this, the US treats sassafras tea and oil of sassafras in food as adulterated.
Leaf (filé) as a food thickener
Not enough evidenceGround sassafras leaf (filé) thickens gumbo. In the 1997 test, most leaf samples had safrole below the detection limit, but this was a small old test.
2 studiesNot specified. Root bark is the part with the safrole concern; leaf (…
Studies, doses and limits
What the trials found
No health trial of filé.
Results
Not applicable.
Effect sizes as reported
None available.
Why this rating
Only 26 samples tested in 1997.
Form and dose studied
Not specified. Root bark is the part with the safrole concern; leaf (filé) is a different product.
Who was studied
Not applicable (no human trials).
Limits
Old test; the 21 CFR 189.180 text does not mention leaves.
Why researchers looked
Leaf powder is a cooking ingredient, not a medicine.
Traditional use
Used in Louisiana cooking (see the filé powder page).
Proposed mechanism Authoritative guidance
Not applicable.
A proposed mechanism does not show that the effect happens in people.
Leaf and root bark are different products; a leaf result does not apply to root bark.
Connections to the rest of health
How Sassafras 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
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Detoxification Support | Traditional use | Not enough evidence | 'Detox' and cleansing: Sassafras root bark tea has been promoted as a 'detox' or spring blood cleanser. No human study shows it does this. | 5 |
| Inflammation Balance | Traditional use | Not enough evidence | Inflammation and arthritis: Sassafras has been used for joint pain and arthritis in folk medicine. No human evidence supports it. | 5 4 |
| Joint Support | Traditional use | Not enough evidence | Inflammation and arthritis: Sassafras has been used for joint pain and arthritis in folk medicine. No human evidence supports it. | 5 4 |
| Digestive Support | Traditional use | Not enough evidence | Fever and diarrhea (traditional): Native American and later folk use of sassafras root bark infusions for fever and diarrhea. Not tested in people. Leaf (filé) as a food thickener: Ground sassafras leaf (filé) thickens gumbo. In the 1997 test, most leaf samples had safrole below the detection limit, but this was a small old test. | 5 1 9 |
| Cellular Protection | Preliminary mechanism | Not enough evidence | Anti-cancer effects in cells and mice: Safrole killed some human cancer cell lines in the lab and affected leukemia cells in mice. This is not a treatment, and safrole itself is a rodent liver carcinogen. | 5 6 |
| Blood Sugar Balance | Preliminary mechanism | Not enough evidence | Blood sugar (rodent studies): One rodent study cited by MSK reported effects of safrole on blood sugar and fats. No human study. | 5 4 |
| Preventive Wellness | Traditional use | Not enough evidence | Flavour and root beer: Sassafras root bark was used to flavour root beer and to scent perfume. That was a flavour use, not a health benefit, and the safrole concern ended it in US food. | 5 9 10 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Hepatic System | Biological association | Not enough evidence | Studied for: 'Detox' and cleansing | 5 |
| Musculoskeletal System | Biological association | Not enough evidence | Studied for: Inflammation and arthritis | 5 4 |
| Digestive System | Biological association | Not enough evidence | Studied for: Fever and diarrhea (traditional) Studied for: Flavour and root beer | 5 9 10 1 |
| Immune System | Biological association | Not enough evidence | Studied for: Anti-cancer effects in cells and mice | 5 6 |
| Endocrine System | Biological association | Not enough evidence | Studied for: Blood sugar (rodent studies) | 5 4 |
C. Body parts and organs
J. Genes, receptors and enzymes
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| CYP3A4 | Preliminary mechanism | In vitro | Key enzyme in the activation of safrole and related flavour chemicals (lab). | 11 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Safrole | Biological association | Authoritative guidance | Liver tumours in rodents; cell-death effects in cancer cell lines (lab). Preparation or compound: Root bark and oil |
9 1 6 7 |
| Isosafrole | Biological association | Authoritative guidance | Named with safrole in the US food rule. Preparation or compound: Derivative of safrole |
9 7 |
| Lignans | Biological association | Not enough evidence | Not described in the sources read; no lignan data were opened this round. Preparation or compound: Not specified |
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).
The evidence
The research centre for Sassafras. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
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 and read abstracts of 5 PubMed papers; read the MSK monograph and the US rules 21 CFR 189.180 and 172.580; checked the plant name in GBIF and compound IDs in PubChem. The NTP safrole profile is cited from an earlier reading and was not re-opened. LiverTox, LactMed, NCCIH and an HMPC monograph were not found.
Study library: every study we checked 11
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Carlson 1997 Liquid chromatographic determination of safrole in sassafras-derived herbal products Journal of AOAC International · PMID 9325580 |
Laboratory analysis product testing |
26 26 sassafras-derived samples (root bark powder, leaves, oils, tea concentrate, tinctures, capsules) |
Sassafras albidum or safrole unspecified |
Safrole ranged from below the detection limit for most leaf samples to 92.4% for an oil. Brewed teas from root bark powders and tinctures contained 0.09 to 4.66 mg safrole per cup. Very wide spread between products Methods, limits and fundingOutcomes: Safrole content Limitations: Small, old (1997) product test by FDA authors; only 26 samples; products on sale today may differ. Funding and conflicts: Not stated. Read: abstract |
| Götz 2023 Occurrence of Alkenylbenzenes in Plants: Flavours and Possibly Toxic Plant Metabolites Plants (Basel) · PMID 37299054 · DOI |
Narrative review review of lab/animal and occurrence data |
Review of alkenylbenzenes (safrole, methyleugenol, estragole) in flavouring plants and oils | Sassafras albidum or safrole unspecified |
Says some alkenylbenzenes, including safrole, are proven genotoxic carcinogens, and that quantitative occurrence data in final foods, supplements and drinks are still limited. No sassafras-specific numbers taken from the abstract Methods, limits and fundingOutcomes: Occurrence of genotoxic alkenylbenzenes Limitations: Abstract only read. Funding and conflicts: Not stated. Read: abstract |
| Haines 1991 Sassafras tea and diaphoresis Postgraduate Medicine · Source |
Case report |
One reported case (cited by MSK) | Sassafras albidum or safrole unspecified |
Cited by MSK as the source of the hot flashes and heavy sweating after sassafras tea. NOT opened. Single case Methods, limits and fundingOutcomes: Sweating after sassafras tea Limitations: Not opened; known only from the MSK reference list. Funding and conflicts: Not stated. Read: summary-only |
| Hegheș 2026 New Insights into the Pharmacological Effects and Potential Health Benefits of Volatile Phenylpropenes Molecules · PMID 42883166 · DOI |
Narrative review lab + animal (as reviewed) |
Review of phenylpropenes (safrole, eugenol, anethole and others) from herbs and spices | Sassafras albidum or safrole unspecified |
Says phenylpropenes, including safrole, have shown antimicrobial, antitumour, antioxidant, anti-inflammatory and antidiabetic effects, mostly in preclinical in vivo and in vitro studies. Preclinical only Methods, limits and fundingOutcomes: Pharmacological effects Limitations: Not about sassafras itself. Abstract only read. Funding and conflicts: Authors declare no conflict of interest. Read: abstract |
| Memorial Sloan Kettering Cancer Center 2023 Sassafras (herb monograph) MSK About Herbs · Source |
Authoritative guidance human + lab + animal (as reviewed) |
Cancer-centre herb monograph | Sassafras albidum or safrole unspecified |
Says studies of sassafras are limited and only in vitro or in animals. Safrole causes liver cancer in animal models and is 'reasonably anticipated to be a human carcinogen'; risk rises with length of exposure and amount. Case report of hot flashes and sweating after sassafras tea. In vitro, safrole inhibited human CYP1A2, CYP2A6 and CYP2E1. Claimed uses (detox, inflammation, arthritis) listed as purported benefits. No human trial evidence of benefit Methods, limits and fundingOutcomes: Uses, mechanisms, warnings, adverse reactions, interactions Limitations: A monograph summarising other sources; the 2023 version cites older references (NTP 14th edition, 1990s books). Funding and conflicts: Not stated. Read: full-text |
| National Toxicology Program (NIEHS) 2021 Report on Carcinogens, 15th Edition: Safrole NTP Report on Carcinogens · Source |
Authoritative guidance animal + regulatory |
US government carcinogen profile | Sassafras albidum or safrole unspecified |
Per our earlier notes (not re-opened in this round, the PDF text could not be decoded): safrole is listed as reasonably anticipated to be a human carcinogen, based on liver tumours in rats and mice; no human cancer studies of safrole specifically; notes that safrole is a DEA List I chemical used in illicit MDMA production. NOT re-verified in this build. Rodent liver tumours; human risk anticipated not measured Methods, limits and fundingOutcomes: Cancer classification of safrole Limitations: summary-only: carried from an earlier reading, not re-opened here. Funding and conflicts: Not stated. Read: summary-only |
| PubChem 2026 Safrole, PubChem compound record PubChem · Source |
Database record chemistry |
Compound record | Sassafras albidum or safrole unspecified |
CID 5144, formula C10H10O2, 5-prop-2-enyl-1,3-benzodioxole. Isosafrole CID 637796. Identity Methods, limits and fundingOutcomes: Identity Limitations: Database record. Funding and conflicts: Not stated. Read: full-text |
| US Drug Enforcement Administration (eCFR) current 21 CFR 1310.02 Substances covered (List I chemicals) Code of Federal Regulations · Source |
Regulation regulatory |
US chemical control rule | Sassafras albidum or safrole unspecified |
Carried from an earlier reading: safrole is a List I chemical. Not re-opened in this round. Legal background about the chemical only Methods, limits and fundingOutcomes: Safrole as a List I chemical Limitations: summary-only Funding and conflicts: Not stated. Read: summary-only |
| US Food and Drug Administration (eCFR) current (text read 2026-10-25) 21 CFR 189.180 Safrole Code of Federal Regulations · Source |
Regulation regulatory |
US food rule | Sassafras albidum or safrole unspecified |
Safrole is a natural constituent of the sassafras plant; oil of sassafras is about 80 percent safrole. Food containing added safrole, oil of sassafras, isosafrole or dihydrosafrole, or sassafras bark intended mainly to flavour another food, for example sassafras tea, is deemed adulterated, based on a Federal Register order of 3 December 1960. Food ban (1960 order) Methods, limits and fundingOutcomes: Status of safrole and oil of sassafras in food Limitations: Applies to food. The rule text does not mention leaves or filé. Funding and conflicts: Not stated. Read: full-text |
| US Food and Drug Administration (eCFR) current (text read 2026-10-25) 21 CFR 172.580 Safrole-free extract of sassafras Code of Federal Regulations · Source |
Regulation regulatory |
US food additive rule | Sassafras albidum or safrole unspecified |
The additive is the aqueous extract of the root bark of Sassafras albidum, made by extracting with dilute alcohol, concentrating, diluting with water and discarding the oily fraction. The purified extract is safrole-free and may be used as a food flavouring. Allowed only if safrole-free Methods, limits and fundingOutcomes: Allowed safrole-free sassafras extract Limitations: Regulation text only; retail 'safrole-free' claims were not checked. Funding and conflicts: Not stated. Read: full-text |
| Yang 2026 Mechanistic Insight into Difference in Hepatotoxicity of Methyleugenol and Safrole Journal of Agricultural and Food Chemistry · PMID 41605223 · DOI |
Laboratory lab |
Lab and computer study of two flavour chemicals | Sassafras albidum or safrole unspecified |
Calls both hepatotoxic flavourings with different IARC groups (methyleugenol 2A, safrole 2B). Methyleugenol was more hepatotoxic than safrole because it is activated more efficiently, with CYP3A4 the key enzyme. Lab only; safrole is the less toxic of the two in this study Methods, limits and fundingOutcomes: Why methyleugenol is more liver-toxic than safrole Limitations: Not a study of sassafras products or people. Abstract only read. Funding and conflicts: Not stated. Read: abstract |
What we do not know yet
- No human trial of sassafras root bark, leaf, tea or extract was found for any use.
- No EMA/HMPC, WHO, NCCIH, LiverTox or LactMed entry was found.
- The only product-testing data are from 1997.
How new research is added
New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it changes any evidence rating.
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".
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 4
- Cancer risk: safrole caused liver tumours in rodents. Safrole, the main oil of sassafras root bark, caused liver cancer in rats and mice. The US National Toxicology Program lists it as reasonably anticipated to be a human carcinogen. It found no human studies of safrole and cancer, so the human risk is anticipated, not measured. MSK says the risk goes up with the amount and length of use, and advises against using sassafras or its oil to treat any condition. Authoritative guidance 5 6
- US food ban. Since 1960 the US has treated food containing added safrole or oil of sassafras, and sassafras bark meant mainly to flavour another food (such as sassafras tea), as adulterated. A root bark extract is allowed only if it is safrole-free. Authoritative guidance 9 10
- Products vary hugely. In a small 1997 FDA test of 26 products, most leaf samples had safrole below detection, one oil had up to 92.4 percent safrole, and brewed root bark teas had 0.09 to 4.66 mg safrole per cup. The form decides the exposure. Product testing 1
- Leaf (filé) is not root bark. Filé powder is made from leaves. Most leaf samples in the 1997 test had safrole below detection, but that test was small and old, and 'safrole-free' labels on retail products were not checked. Product testing 1 9
Side effects 2
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Liver cancer (rodents) Human cancer risk is anticipated, not measured, and not shown to be zero. | Not given for people; shown in rats and mice. | severe Not applicable (cancer) | Authoritative guidance 6 5 |
| Hot flashes and heavy sweating The original report was not opened. | One case report after sassafras tea (cited by MSK); no rate. | mild Not stated in the sources read. | Case report 5 3 |
Liver
No LiverTox entry for sassafras was found (a Bookshelf search returned none). In rodents safrole causes liver tumours. A 2026 lab study found safrole liver-toxic through CYP3A4 activation, though less than methyleugenol. No case of liver injury in people from sassafras was found in the sources read. 6 5 11
How often. No rate for people.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Sassafras supports liver health.
Medicines and supplements 1
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Medicines cleared by liver enzymes CYP1A2, CYP2A6, CYP2E1 prescription | MSK says safrole inhibited these human enzymes in vitro. | Unknown. Lab finding only; no effect in people is described. | Laboratory research Very low certainty 5 | Tell your doctor or pharmacist if you have used sassafras products and take regular medicines. |
Who should check first 3
| Situation | Advice | Evidence |
|---|---|---|
| Pregnancy and breastfeeding | No agency statement on sassafras in pregnancy was found (LactMed entry not found). Given the cancer warning, avoiding sassafras root bark and oil is a reasonable reading, but that is our reading, not an agency rule. Ask a doctor or pharmacist. | Pharmacological theory 5 |
| Children | No data found. The cancer concern applies; ask a doctor. | Pharmacological theory 5 |
| Liver disease | Safrole is a rodent liver carcinogen; ask a doctor before using any sassafras root bark product. | Pharmacological theory 6 5 |
Overdose, product quality and regulators
Summary. The concern is safrole, concentrated in root bark and especially in the oil (about 80 percent safrole per US regulation).
Animal. Safrole caused liver tumours in rats and mice (NTP).
Human doses studied. None; no dose study in people.
High dose or long term signals. MSK says the risk increases with amount and length of exposure.
Overdose response. Not covered in the sources read.
Genotoxicity. A 2023 review names safrole among the widely known genotoxic alkenylbenzenes.
Toxic plant parts. Root bark and oil carry the safrole concern; leaves tested very low in 1997.
The main quality issue is how much safrole a product holds; nothing was found on pesticides, metals or microbes.
Safrole content varies. Below detection in most leaf samples to 92.4 percent in one oil; teas 0.09-4.66 mg per cup (1997, 26 samples). 1
Safrole-free claims. US rules allow a safrole-free root bark extract as a flavouring. Retail 'safrole-free' claims were not checked. 10
| Body | Action | Date |
|---|---|---|
| US Food and Drug Administration (21 CFR 189.180) (United States) | Food with added safrole or oil of sassafras, or sassafras bark meant to flavour another food (such as sassafras tea), is deemed adulterated. source | 1960 order; text read 2026-10-25 |
| US Food and Drug Administration (21 CFR 172.580) (United States) | Safrole-free extract of sassafras root bark may be used as a flavouring. source | text read 2026-10-25 |
When to get medical help
- Yellow skin or eyes, dark urine or ongoing upper-right belly pain: see a doctor (general advice for possible liver trouble; no sassafras liver case was found).
- Heavy sweating or flushing after sassafras tea: stop and seek advice (one case report).
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 sassafras?
Sassafras is a tree of the eastern United States, Sassafras albidum. Its root bark was used for tea and to flavour root beer, and its leaves are ground into filé powder for cooking.
Is sassafras tea safe?
Why did the US ban safrole and oil of sassafras in food?
Does sassafras cause cancer in people?
What is filé powder, and is it the same?
Are there safrole-free sassafras products?
US rules allow a root bark extract as a food flavouring only if it is safrole-free. We could not check retail claims, so a label alone is hard to trust.
How much safrole is in different products?
In a 1997 test of 26 products, most leaf samples were below detection, one oil had up to 92.4 percent safrole, and brewed root bark teas had 0.09 to 4.66 mg per cup.
Does sassafras work for detox, arthritis or fever?
No human study supports these uses. MSK found no scientific evidence for the claimed uses, and the plant carries a cancer warning.
Can sassafras interact with medicines?
In lab tests safrole blocked the liver enzymes CYP1A2, CYP2A6 and CYP2E1. No effect in people is described. Tell your doctor or pharmacist about any sassafras products you use.
Is sassafras safe in pregnancy or for children?
No agency statement on sassafras was found. Given the cancer warning, avoiding it is a sensible reading, but that is our reading. Ask a doctor or pharmacist.
Are the cancer-cell studies a reason to try it?
No. They are lab and mouse studies, and MSK says they do not offset safrole's cancer-causing potential.
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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 and read abstracts of 5 PubMed papers; read the MSK monograph and the US rules 21 CFR 189.180 and 172.580; checked the plant name in GBIF and compound IDs in PubChem. The NTP safrole profile is cited from an earlier reading and was not re-opened. LiverTox, LactMed, NCCIH and an HMPC monograph were not 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, and none will be added for sassafras.
Sources 11
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Carlson M, Thompson RD. Liquid chromatographic determination of safrole in sassafras-derived herbal products. Journal of AOAC International. 1997. PMID 9325580. (abstract)
- Götz ME, et al. Occurrence of Alkenylbenzenes in Plants: Flavours and Possibly Toxic Plant Metabolites. Plants (Basel). 2023. PMID 37299054. DOI 10.3390/plants12112075. (abstract)
- Haines JD. Sassafras tea and diaphoresis. Postgraduate Medicine. 1991. (summary-only)
- Hegheș SC, et al. New Insights into the Pharmacological Effects and Potential Health Benefits of Volatile Phenylpropenes. Molecules. 2026. PMID 42883166. DOI 10.3390/molecules31193400. (abstract)
- Memorial Sloan Kettering Cancer Center. Sassafras (herb monograph). MSK About Herbs. 2023. (full-text)
- National Toxicology Program (NIEHS). Report on Carcinogens, 15th Edition: Safrole. NTP Report on Carcinogens. 2021. (summary-only)
- PubChem. Safrole, PubChem compound record. PubChem. 2026. (full-text)
- US Drug Enforcement Administration (eCFR). 21 CFR 1310.02 Substances covered (List I chemicals). Code of Federal Regulations. current. (summary-only)
- US Food and Drug Administration (eCFR). 21 CFR 189.180 Safrole. Code of Federal Regulations. current (text read 2026-10-25). (full-text)
- US Food and Drug Administration (eCFR). 21 CFR 172.580 Safrole-free extract of sassafras. Code of Federal Regulations. current (text read 2026-10-25). (full-text)
- Yang H, et al. Mechanistic Insight into Difference in Hepatotoxicity of Methyleugenol and Safrole. Journal of Agricultural and Food Chemistry. 2026. PMID 41605223. DOI 10.1021/acs.jafc.5c13276. (abstract)