Safety Profile
Known Safety Concerns
- ESTRAGOLE: possibly carcinogenic/genotoxic (IARC 2B); phytoestrogenic (anethole); fenchone neurotoxic at high doses; CONTRAINDICATED in infants, young children, and pregnancy
Contraindications
- ESTRAGOLE: possibly carcinogenic/genotoxic (IARC 2B); phytoestrogenic (anethole); fenchone neurotoxic at high doses; CONTRAINDICATED in infants, young children, and pregnancy
Interactions
Information not yet available for this ingredient profile.
Evidence and Scientific Findings
Ingredient Overview
Fennel essential oil is steam-distilled from Foeniculum vulgare seeds (fruit). Primary constituents: trans-anethole (50–80%), fenchone (10–25%), limonene, and estragole (methyl chavicol 1–5%). Medicinal use of fennel herbal preparations is documented for: carminative (reduces gas/bloating), antispasmodic (GI smooth muscle relaxation), mild galactagogue (traditional). CRITICAL SAFETY CONCERNS: (1) ESTRAGOLE — a potentially genotoxic and carcinogenic constituent (EFSA Scientific Committee 2001): classified as Category 2B carcinogen (possibly carcinogenic to humans) by IARC based on animal data; liver carcinogen in rodents; DNA adducts demonstrated in in vitro studies. The European Medicines Agency recommends limiting estragole exposure; products should disclose estragole content. Acceptable daily intake has not been established. (2) TRANS-ANETHOLE — phytoestrogenic activity (weak oestrogen receptor agonist); may affect menstrual cycle regularity at high doses. (3) FENCHONE — neurotoxic at high doses (similar to camphor — GABA-A antagonist). Fennel essential oil use in infants and young children is CONTRAINDICATED (neurotoxicity, hormonal effects). PREGNANCY: avoid concentrated EO — anethole is a uterotonic; may stimulate uterine contractions. EU: maximum permitted concentration in cosmetics is limited. Herbal tea from fennel seeds (standardised, low-concentration preparation) is distinct from concentrated essential oil and is generally considered safe at food doses for adults. Drug interactions: possible CYP1A2 interactions. Epilepsy: avoid (fenchone lowers seizure threshold).
Biological and Chemical Classification
- Scientific Name
- Foeniculum vulgare
Mechanism of Action
Information not yet available for this ingredient profile.
Clinical Evidence of Effectiveness
Information not yet available for this ingredient profile.
Pharmacokinetics
Information not yet available for this ingredient profile.
Recommended Dosage
Information not yet available for this ingredient profile.
SETI — Scientific Evidence Transparency Index
Executive Summary — Ingredient Assessment
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or RCT)
- Main clinical benefit observed: Botanical
- Evidence consistency: High consistency across studies (100%)
- ESTRAGOLE: possibly carcinogenic/genotoxic (IARC 2B); phytoestrogenic (anethole); fenchone neurotoxic at high doses; CONTRAINDICATED in infants, young children, and pregnancy
The available scientific evidence for Fennel Essential Oil indicates notable safety signals that warrant caution. Use should be considered carefully and monitored, particularly in sensitive populations or alongside other medications.
Total SETI Score
High risk| Evidence quality | 10/40 |
| Evidence consistency | 20/20 |
| Safety signals | 0/20 |
| Study recency | 10/10 |
| Evidence transparency | 10/10 |
Evidence Summary
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or systematic review)
- 0 studies identified benefits or no safety concern (GREEN)
- 10 studies reported limited or advisory safety evidence (YELLOW)
Evidence Policy
Only peer-reviewed scientific literature indexed in PubMed or comparable databases is included in this evaluation. Commercial websites, blogs, and marketing materials are excluded. All references include direct traceable links to source documents.
Last updated: 06 აპრ 2026, 12:08
Evidence Distribution
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Observational / other LOW evidence YELLOWSoil accumulation and plant uptake of pharmaceutical active compounds and related metabolites from irrigation water in fennel (Foeniculum vulgare Mill.). ↗Gatta G et al.. Soil accumulation and plant uptake of pharmaceutical active compounds and related metabolites from irrigation water in fennel (Foeniculum vulgare Mill.).. Front Plant Sci. 2026. PMID:41809629.PMID 41809629 ↗Journal Front Plant SciYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41809629/
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Observational / other LOW evidence YELLOWThe association between medicinal herbs consumption and body weight and composition: a hospital based cross-sectional study. ↗Arabi V et al.. The association between medicinal herbs consumption and body weight and composition: a hospital based cross-sectional study.. Sci Rep. 2026. PMID:41775830.PMID 41775830 ↗Journal Sci RepYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41775830/
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Observational / other LOW evidence YELLOWIn-silico interaction of molecules from Foeniculum vulgare methanolic seed extract with conserved RNA binding residues of NS3 protein of Dengue virus. ↗Tazeen A et al.. In-silico interaction of molecules from Foeniculum vulgare methanolic seed extract with conserved RNA binding residues of NS3 protein of Dengue virus.. J Biomol Struct Dyn. 2026. PMID:41762031.PMID 41762031 ↗Journal J Biomol Struct DynYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41762031/
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Observational / other LOW evidence YELLOWConventional and Rock-Based Potassium Fertilization Improves Fennel (Foeniculum vulgare Mill.) Performance Under Extended Irrigation Intervals. ↗El-Sheref GFH et al.. Conventional and Rock-Based Potassium Fertilization Improves Fennel (Foeniculum vulgare Mill.) Performance Under Extended Irrigation Intervals.. Plants (Basel). 2026. PMID:41754280.PMID 41754280 ↗Journal Plants (Basel)Year 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41754280/
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Observational / other LOW evidence YELLOWIn Vitro Evaluation of Ethanolic Medicinal Plant Extracts from the Aseer Region Against Selected Cultured Oral Bacterial Isolates from Healthy Volunteers. ↗Noor S et al.. In Vitro Evaluation of Ethanolic Medicinal Plant Extracts from the Aseer Region Against Selected Cultured Oral Bacterial Isolates from Healthy Volunteers.. Microorganisms. 2026. PMID:41753785.PMID 41753785 ↗Journal MicroorganismsYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41753785/
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Observational / other LOW evidence YELLOWA Green Shield for Copper: Corrosion Inhibition by Fennel (Foeniculum vulgare) Seed Extract Revealed through Experiments and Modeling. ↗Zheng R et al.. A Green Shield for Copper: Corrosion Inhibition by Fennel (Foeniculum vulgare) Seed Extract Revealed through Experiments and Modeling.. Langmuir. 2026. PMID:41693663.PMID 41693663 ↗Journal LangmuirYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41693663/
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Observational / other LOW evidence YELLOWImpact of dietary supplementation with fennel seed (Foeniculum vulgare var. dulce) on growth Performance, carcass characteristics, meat quality, intestinal measurements, and cecal… ↗Saidani M et al.. Impact of dietary supplementation with fennel seed (Foeniculum vulgare var. dulce) on growth Performance, carcass characteristics, meat quality, intestinal measurements, and cecal microbiota in broiler chickens.. Trop Anim Health Prod. 2026. PMID:41677793.PMID 41677793 ↗Journal Trop Anim Health ProdYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41677793/
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Observational / other LOW evidence YELLOWEfficacy of herbaceous Apiaceae plants in primary dysmenorrhea: A systematic review and meta-analysis of RCTs. ↗Thaliyil Poduval A et al.. Efficacy of herbaceous Apiaceae plants in primary dysmenorrhea: A systematic review and meta-analysis of RCTs.. Ann Pharm Fr. 2026. PMID:41653970.PMID 41653970 ↗Journal Ann Pharm FrYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41653970/
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Observational / other LOW evidence YELLOWGreen synthesis of polypyrrole-SnO(2) nanocomposites using Foeniculum vulgare extract for crystal violet adsorption and solvent-dependent radical scavenging. ↗Kaushik P et al.. Green synthesis of polypyrrole-SnO(2) nanocomposites using Foeniculum vulgare extract for crystal violet adsorption and solvent-dependent radical scavenging.. RSC Adv. 2026. PMID:41641233.PMID 41641233 ↗Journal RSC AdvYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41641233/
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Observational / other LOW evidence YELLOWCombined Prebiotic Extract of Mung Bean, Red Bean, and Fennel Improves Intestinal Barrier Integrity in HT-29 Cells and DSS-Induced Colitis via Gut… ↗Lee CS et al.. Combined Prebiotic Extract of Mung Bean, Red Bean, and Fennel Improves Intestinal Barrier Integrity in HT-29 Cells and DSS-Induced Colitis via Gut Microbiota Alteration.. Curr Issues Mol Biol. 2025. PMID:41614862.PMID 41614862 ↗Journal Curr Issues Mol BiolYear 2025Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41614862/
Score Transparency
0 of 10 approved references (score saturates at 10). More peer-reviewed studies = stronger evidence base.
Method: Q = number of approved references ÷ 10 (capped at 1.0)
Limited — mostly case reports or animal studies
Method: L = mean study-level weight across approved references. Level 1 (meta-analysis / systematic review) = 1.0; Level 2 (RCT) = 0.8; Level 3 (cohort/case-control) = 0.6; Level 4 (case report) = 0.4; Level 5 (animal / in-vitro) = 0.2.
Mixed or neutral — roughly equal benefit and risk signals
Method: D = (sum of risk-scored references − sum of benefit-scored references) ÷ total evidence score, then scaled from [−1, 1] to [0, 1]. 0.0 = pure benefit; 0.5 = neutral; 1.0 = pure risk.
One or more monitoring-level safety signals active
Method: S = 0.5 (neutral baseline) + sum of active signal severity deltas ÷ 10. Severity deltas: Critical = +2.0, High = +1.5, Moderate = +1.0, Low = +0.5. Capped at 1.0.
Final GIRI Score for Fennel Essential Oil. Risk level thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.
Full methodology & data sources
The GIRI Score is computed entirely from structured data — no editorial scoring or subjective weighting is applied at any step.
- References: Only approved references are counted. Each reference is assigned an evidence level (L1–L5) and a direction (risk / neutral / benefit) by the reference manager or AI classifier.
- Safety Signals: Sourced from regulatory agencies (FDA, EMA, Health Canada, TGA, and others) and pharmacovigilance databases. Only active signals count toward the score.
- Formula version: GIRI Score v3.7.0 — Q × L × D × S × 10.
- Limitations: The score reflects published evidence and recorded signals as of the last update date. It is not a clinical risk assessment and should not replace advice from a qualified healthcare professional.
Risk Level Classification
Based on available regulatory signals and scientific evidence, this ingredient presents a high safety concern. Its use in dietary supplements is associated with documented adverse events.
0–3.0
3.0–5.5
5.5–7.5
7.5–10
The score pin shows exactly where this ingredient falls on the fixed risk scale.
What drove the High classification for Fennel Essential Oil
A score of 6.0 places this ingredient in the High band. Thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.
0 approved references.
Limited — mostly case reports or animal studies (Level 4–5).
Neutral or mixed — benefit and risk signals roughly balanced.
No active signals — S component is at neutral baseline (0.5), contributing no extra risk weight.
No major regulatory restrictions or advisories recorded across monitored jurisdictions (FDA, EMA, Health Canada, TGA, and others).
How are the Low / Moderate / High / Critical thresholds defined?
The four risk levels are fixed score bands. A score is assigned to exactly one level based on where it falls:
| Level | Score | Meaning |
|---|---|---|
| LOW | 0.0 – 2.9 | Sparse or predominantly beneficial evidence. No active safety alerts. |
| MODERATE | 3.0 – 5.4 | Mixed signals — some risk alongside benefit. Caution at high doses or in sensitive groups. |
| HIGH | 5.5 – 7.4 | Multiple studies or regulatory alerts documenting adverse effects. Professional oversight recommended. |
| CRITICAL | 7.5 – 10 | Regulatory restrictions in one or more major jurisdictions. Serious documented harm. Avoid without specialist supervision. |
Thresholds are fixed constants (GIRI_Score_Utils::LEVEL_THRESHOLDS). They do not change per ingredient and are never subject to editorial adjustment.