Fennel - Tamoxifen Citrate Interaction
Herbal: Fennel
Also Known As: Foeniculum vulgare, Adas, Almindelig fennikel, Arapsaci, Badian, Badishep, Bari-Sanuf, Bisbas, Bitterfenchel, Bitter Fennel, Carosella, Common Fennel, Dunkler Fenchel, Endro, Erva-doce, Fänkål, Fenchel, Fenchle, Fenkuł, Fennel Essential Oil, Fennel Oil, Fennel Seed, Fenneru
Drug: Tamoxifen Citrate
Brand names:
Nolvadex, Soltamox
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jun 23, 2024
Interaction Details
Tamoxifen Citrate is classified as belonging to the following category: 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.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- 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.
- 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
Interaction Details
Tamoxifen Citrate is classified as belonging to the following category: 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.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
Fennel Overview
Fennel is a plant species in the carrot family and native to the Mediterranean region. Fennell seeds are often used as a spice, and other parts as food.
Fennel has a distinctive, sweet, licorice-like flavor and is often used in cooking to add flavor to dishes such as sauces, salads, and baked goods. It is used in traditional medicine as a good source of vitamins and minerals, such as potassium, beta-carotene and vitamin C. It has also been used to treat a variety of conditions, including digestive issues, respiratory problems, and skin conditions.
Tamoxifen Citrate Overview
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Tamoxifen is used to treat breast cancer that has spread to other parts of the body in men and women. It is used to treat early breast cancer in women who have already been treated with surgery, radiation, and/or chemotherapy. It is used to reduce the risk of developing a more serious type of breast cancer in women who have had ductal carcinoma in situ (DCIS; a type of breast cancer that does not spread outside of the milk duct where it forms) and who have been treated with surgery and radiation. It is used to reduce the risk of breast cancer in women who are at high risk for the disease due to their age, personal medical history, and family medical history.
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Tamoxifen is in a class of medications known as antiestrogens. It blocks the activity of estrogen (a female hormone) in the breast. This may stop the growth of some breast tumors that need estrogen to grow.
Fennel - More Interactions
Fennel interacts with 716 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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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
Drug descriptions are provided by MedlinePlus.
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Dr. Brian Staiger, PharmD
In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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