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Dietary supplement

Fennel Ingredients & Drug Interactions

by Zongle Therapeutics

Fennel label
See full label image
Liquid Category: Botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Fennel against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Fennel is a dietary supplement by Zongle Therapeutics with 1 active ingredient. Its ingredients are commonly taken for digestive upset and bloating, infant colic, menstrual cramps.Based on those ingredients, 740 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Fennel. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Fennel by Zongle Therapeutics

Ask about any prescription or over-the-counter medication and we check it for interactions with Fennel by Zongle Therapeutics — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Fennel by Zongle Therapeutics

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 30, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This is a straightforward single-ingredient product: fennel in liquid form. The active ingredient is fennel itself, along with fennel oil that has been steam-distilled — the oil is also an inactive ingredient in this formulation.

There's just the one active ingredient doing the work here.

Does it work?

Not established
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use — see Fennel's own graded uses on its monograph.

Why this rating?
  • The label markets this product for: promotes healthy digestion and digestive tract.
  • We looked for evidence on: Dyspepsia, Flatulence, Colic, Nausea and vomiting, Constipation, Irritable bowel syndrome (IBS) — and 3 related terms.
  • The closest evidence on file: Fennel is rated "Insufficient Reliable Evidence To Rate" for Constipation (Natural Medicines).
  • Also on file: Fennel is rated "Insufficient Reliable Evidence To Rate" for Dyspepsia, Flatulence, Irritable bowel syndrome (IBS), Nausea and vomiting, and more.

Fennel is possibly effective for menstrual cramps (dysmenorrhea). For other uses listed — bronchitis, anxiety, bedwetting, and cholera — we don't have enough reliable evidence yet to say whether it works.

If you're considering it for dysmenorrhea, that's the one use where there's some support; for anything else, the evidence isn't established in the data we hold.

The evidence, ingredient by ingredient Fennel

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Fennel is generally well tolerated when you use it as a food. Concentrated supplements and essential oils call for more caution.

Most side effects are mild — gastrointestinal discomfort, sensitivity to sunlight, and allergic reactions in people who are sensitive to it. Seizures have been reported rarely.

Some people have had allergic reactions to fennel-containing products (sneezing, coughing, wheezing, and difficulty breathing), and in rare cases fennel can trigger bronchial asthma. The safety data advises against medicinal or concentrated amounts during pregnancy because of limited safety information and fennel's hormone-like effects.

During breastfeeding, food amounts are probably fine, but medicinal doses and the essential oil aren't well studied — talk with your doctor or pharmacist about what's right for you.

Side effects, ingredient by ingredient Fennel

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Fennel.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs.
  • For scale: 741 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this fennel liquid, double-check with your doctor or pharmacist if you're on blood thinners (anticoagulants or antiplatelets like warfarin or aspirin), birth control pills, hormone replacement therapy, tamoxifen, ciprofloxacin, or any medications your liver metabolizes through the CYP3A4 pathway — fennel may affect how all of these work.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Moderate medication interactions have been identified, and safety information is well characterized.

Fennel may help with menstrual cramps, but this product interacts with blood thinners, birth control, hormone therapy, some antibiotics, and drugs metabolized by your liver — so it's not a grab-and-go choice. If you take any prescription medication, especially the types listed above, check with your doctor or pharmacist before you add this.

Pregnant or breastfeeding? That's another conversation to have with them first.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Oct 24, 2022.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Fennel, straight from the product label.

Brand Zongle Therapeutics
Net contents 0.5 Fluid Ounce(s); 15 mL
Market status On market
Date entered into DSLD Oct 24, 2022
DSLD ID 277105
Product type Botanical
Supplement form Liquid
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Gluten Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Fennel by Zongle Therapeutics, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Drop(s)
Maximum serving Sizes:
1 Drop(s)
Servings per container
250
IngredientAmount% DV
Fennel60 mg--

Other ingredients: Fennel Oil, Steam-Distilled

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Formulation

Promotes healthy digestion Supports healthy digestive tract May help fight sweet tooth cravings Promotes healthy metabolism Calming and soothing

100% Pure Therapeutic Grade

Origin: Hungary Bottled in USA

Artificial ingredients free GMO free Gluten free Preservatives free Paraben free

Vegan

Suggested/Recommended/Usage/Directions

For aromatic, topical or internal use. For internal use dilute one drop in 4 fl. oz. of liquid. Dilute for kids or sensitive skin.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Precautions

Caution: Possible skin sensitivity.

Keep out of reach of children.

If you are pregnant, nursing, or under a doctor's care, consult your physician.

Avoid contact with eyes, inner ears, and sensitive areas.

Formula

Foeniculum vulgare

FDA Statement of Identity

Essential Oil Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Fennel by Zongle Therapeutics label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Fennel label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Fennel by Zongle Therapeutics

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Drop(s) Dosage formLiquid Servings per container250 Amounts shown are per serving.

Fennel

Interacts with
740 drugs
60 mg per serving

Fennel is a Mediterranean herb widely used as a food and spice, and traditionally taken for digestive complaints, colic, and menstrual cramps. Some sm...

Fennel monograph & interactions

Other (inactive) ingredients: Fennel Oil, Steam-Distilled. These complete the product’s ingredient list but are not active constituents.

Interaction report

Fennel by Zongle Therapeutics Drug Interactions

Want to check YOUR meds against Fennel?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
740Drugs
740 Moderate

Ingredients driving the most interactions

Fennel 740

Individual Drug Interactions

The ingredients in Fennel interact with 740 drugs. Click any drug to see the details.

1 of the 1 ingredient in Fennel interact with drugs. Each result below shows which ingredient is responsible. Fennel

Each ingredient & the kinds of drugs it affects

For each ingredient in Fennel with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Fennel6 drug types · 740 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, fennel might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.

Animal research suggests that fennel oil has antithrombotic and antiplatelet effects.

Likelihood Possible Evidence D
Ciprofloxacin (Cipro)

Theoretically, fennel might decrease the levels and clinical effects of ciprofloxacin.

Animal research shows that fennel reduces ciprofloxacin bioavailability by nearly 50%, possibly due to the metal cations such as calcium, iron, and magnesium contained in fennel. This study also found that fennel increased tissue distribution and slowed elimination of ciprofloxacin.

Likelihood Probable Evidence D
Contraceptive Drugs

Theoretically, taking large amounts of fennel might decrease the effects of contraceptive drugs due to competition for estrogen receptors.

Some constituents of fennel have estrogenic activity.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, fennel might increase levels of drugs metabolized by CYP3A4.

In vitro research suggests that fennel inhibits CYP3A4 enzyme activity. This effect has not been reported in humans.

Likelihood Possible Evidence D
Estrogens

Theoretically, taking large amounts of fennel might interfere with hormone replacement therapy due to competition for estrogen receptors.

Some constituents of fennel have estrogenic activity.

Likelihood Possible Evidence D
Tamoxifen (Nolvadex)

Theoretically, taking large amounts of fennel might decrease the antiestrogenic effect of tamoxifen.

Some constituents of fennel have estrogenic activity, which may interfere with the antiestrogenic activity of tamoxifen.

Likelihood Possible Evidence D
Fennel full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Fennel, from the product label.

Zongle Therapeutics

See all Zongle Therapeutics products
Name
Zongle Therapeutics
Web Address
www.zongletherapeutics.com
Pharmacist Counseling Corner

Fennel by Zongle Therapeutics: Common Questions

Does Fennel by Zongle Therapeutics interact with any medications?
Yes. Based on its ingredients, Fennel has a known interaction with 740 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Fennel contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Does fennel actually work for menstrual cramps?
Yes — fennel is possibly effective for dysmenorrhea (menstrual cramps). For other conditions like bronchitis or anxiety, we don't have enough reliable evidence to say it works.
Is this safe to use if I'm pregnant?
No — the safety data advises against medicinal or concentrated amounts during pregnancy because there's limited safety information and fennel has hormone-like effects. Talk with your doctor or pharmacist about what's safe for you.
Can I take this while breastfeeding?
Food amounts of fennel are probably fine, but medicinal doses and fennel essential oil aren't well studied while breastfeeding. Check with your doctor or pharmacist about what dose is right for you.
What side effects might I experience?
Most people tolerate fennel well. The most common side effects are mild — stomach discomfort, sensitivity to sunlight, and allergic reactions if you're sensitive to it. Seizures and asthma have been reported very rarely.
What is fennel used for?
Fennel is used in herbal medicine mainly for menstrual cramps, where there's some evidence it may help. People also try it for bronchitis, anxiety, and other conditions, but we don't have strong evidence for those uses yet.
Will fennel affect my birth control?
Possibly — fennel has compounds with estrogenic activity, which theoretically could reduce how well birth control works. Talk to your doctor before using this product alongside hormonal contraceptives.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Fennel label
Go deeper

The Full Monographs Behind Fennel’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Fennel

Interacts with 740 drugs

Fennel is a Mediterranean herb widely used as a food and spice, and traditionally taken for digestive complaints, colic, and menstrual cramps. Some small studies suggest possible benefit for...

Read the full Fennel monograph →
Sources

Sources & How We Checked

Fennel's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 17 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Fennel 17 references
  1. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Zhu M, Wong PY, Li RC. Effect of oral administration of fennel (Foeniculum vulgare) on ciprofloxacin absorption and disposition in the rat. J Pharm Pharmacol 1999;51:1391-6.
  4. Gral N, Beani JC, Bonnot D, et al. [Plasma levels of psoralens after celery ingestion]. Ann Dermatol Venereol 1993;120:599-603.
  5. Burkhard PR, Burkhardt K, Haenggeli CA, Landis T. Plant-induced seizures: reappearance of an old problem. J Neurol 1999;246:667-70. PubMed
  6. Rosti L, Nardini A, Bettinelli ME, Rosti D. Toxic effects of a herbal tea mixture in two newborns. Acta Paediatrica 1994;83:683. PubMed
  7. Cuzzolin L, Zaffani S, and Benoni G. Safety implications regarding use of phytomedicines. Eur.J Clin Pharmacol. 2006;62:37-42. PubMed
  8. Tognolini, M., Ballabeni, V., Bertoni, S., Bruni, R., Impicciatore, M., and Barocelli, E. Protective effect of Foeniculum vulgare essential oil and anethole in an experimental model of thrombosis. Pharmacol.Res 2007;56(3):254-260. PubMed
  9. Subehan, Usia, T., Iwata, H., Kadota, S., and Tezuka, Y. Mechanism-based inhibition of CYP3A4 and CYP2D6 by Indonesian medicinal plants. J Ethnopharmacol. 5-24-2006;105(3):449-455. PubMed
  10. Tognolini, M., Barocelli, E., Ballabeni, V., Bruni, R., Bianchi, A., Chiavarini, M., and Impicciatore, M. Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity. Life Sci. 2-23-2006;78(13):1419-1432. PubMed
  11. Subehan, Zaidi, S. F., Kadota, S., and Tezuka, Y. Inhibition on human liver cytochrome P450 3A4 by constituents of fennel (Foeniculum vulgare): identification and characterization of a mechanism-based inactivator. J Agric.Food Chem. 12-12-2007;55(25):101 PubMed
  12. LEVY, S. B. Bronchial asthma due to ingestion of fennel and fennel seed. Ann.Allergy 1948;6(4):415.
  13. Ottolenghi, A., De Chiara, A., Arrigoni, S., Terracciano, L., and De Amici, M. [Diagnosis of food allergy caused by fruit and vegetables in children with atopic dermatitis]. Pediatr Med Chir 1995;17(6):525-530.
  14. Trabace L, Tucci P, Ciuffreda L, et al. "Natural" relief of pregnancy-related symptoms and neonatal outcomes: above all do no harm. J Ethnopharmacol. 2015;174:396-402. PubMed
  15. Denaxa D, Arkwright PD. Fennel as a cause of immediate hypersensitivity to toothpaste. Ann Allergy Asthma Immunol. 2020;125(1):99-100. PubMed
  16. Lee HW, Ang L, Lee MS, Alimoradi Z, Kim E. Fennel for reducing pain in primary dysmenorrhea: a systematic review and meta-analysis of randomized controlled trials. Nutrients 2020;12(11):3438. PubMed
  17. Mathew T, John SK, Javali M, Vasireddy M, Nadig R, Sarma GRK. Substance use related cluster headache: A case series. Headache 2022;62(7):908-910. PubMed

See these in context on the Fennel monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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