Herb & supplement monograph

Bishop's Weed Drug Interactions, Uses, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Bishop's Weed interacts with medications. The heart of this page is the interaction list — every drug Bishop's Weed is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Bishop's Weed is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Bishop's Weed Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Bishop's Weed drug interaction appears low for most people, though the profile deserves some respect because none of it has been ruled out in humans. None of the listed interactions are rated major, and every one is graded as only possible, meaning it comes from lab research or theory rather than confirmed human studies.

Interactions deserving the most attention

The combinations most worth watching involve blood thinners such as warfarin, aspirin, or clopidogrel, because a plant compound in Bishop's Weed has shown antiplatelet activity that could, in theory, add to bleeding risk. That same compound may also slow an enzyme the body uses to clear many common medicines, which could raise blood levels of drugs like alprazolam, amitriptyline, or amiodarone. Bishop's Weed can also make skin more sun-sensitive, so pairing it with photosensitizing drugs like tetracycline or sulfa antibiotics might increase that effect.

What the rest of the list means

The long list of interacting medications looks alarming, but it mostly reflects a few broad drug categories rather than hundreds of separate proven problems. Nearly all of these concerns come from lab findings about how the herb might affect drug clearance or skin sensitivity, and none have been confirmed to cause meaningful changes in people so far.

Check your medications against Bishop's Weed

Based on HelloPharmacist’s Bishop's Weed interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Bishop's Weed

954 medications have a known interaction with Bishop's Weed, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Bishop's Weed using our pharmacist-reviewed interaction data.

AI summaries are generated from our Bishop's Weed interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Bishop's Weed combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Bishop's Weed affects

Every type of medication (drug category) Bishop's Weed is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 3 drug categories Bishop's Weed interacts with

Anticoagulant/antiplatelet DrugsCytochrome P450 3a4 (cyp3a4) SubstratesPhotosensitizing Drugs

Anticoagulant/Antiplatelet Drugs

Bergapten, a constituent of bishop's weed, has antiplatelet activity. Theoretically, bishop's weed might have additive effects with anticoagulant or antiplatelet drugs and possibly increase the risk of bleeding.
Some anticoagulant or antiplatelet drugs include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.

Likelihood Possible Evidence D

Cytochrome P450 3A4 (Cyp3A4) Substrates

Bergapten, a constituent of bishop's weed, has been shown to inhibit cytochrome P450 3A4 (CYP3A4) in vitro. Theoretically, bishop's weed might inhibit elimination and increase blood levels of drugs metabolized by CYP3A4.
Some drugs metabolized by CYP3A4 include alprazolam (Xanax), amitriptyline (Elavil), amiodarone (Cordarone), buspirone (Buspar), cerivastatin (Baycol), citalopram (Celexa), felodipine (Plendil), fexofenadine (Allegra), itraconazole (Sporanox), ketoconazole (Nizoral), lansoprazole (Prevacid), losartan (Cozaar), lovastatin (Mevacor), ondansetron (Zofran), prednisone (Deltasone, Orasone), sertraline (Zoloft), sibutramine (Meridia), sildenafil (Viagra), simvastatin (Zocor), verapamil (Calan, Covera-HS, Isoptin), and many others.

Likelihood Possible Evidence B

Photosensitizing Drugs

Bishop's weed constituents seem to cause photosensitivity. Theoretically, concomitant use of bishop's weed with photosensitizing drugs might result in increased photosensitivity.
Some drugs that cause photosensitivity include amitriptyline (Elavil), quinolones (Ciprofloxacin, others), sulfa drugs (Septra, Bactrim, others), and tetracycline.

Likelihood Possible Evidence D

Monograph

Bishop's Weed: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Bishop's Weed (Ammi majus) is a flowering plant whose seeds contain natural light-sensitizing compounds called psoralens, which have been studied mainly for skin conditions like vitiligo and psoriasis when combined with light therapy. The plant is potentially toxic and can cause severe skin and eye reactions when exposed to sunlight, so it is not something to take on your own. If you are interested in psoralen-based treatments, work with a dermatologist rather than self-treating.

Scientific name: Ammi majus
Family: Apiaceae
Part used: Seeds (fruit) and the extracted compounds (furanocoumarins)
Common forms: Seed extracts, topical preparations, and isolated compounds (such as standardized psoralens used in some skin treatments)

People commonly use it for

Vitiligo (loss of skin color)
Psoriasis
Digestive complaints
Asthma and breathing problems
Kidney stones
Diuretic (increasing urine)

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

The plant contains light-sensitizing compounds and can be toxic; use only under medical supervision.

PregnancyLikely Unsafe

When used orally. Khellin, a constituent of bishop's weed, has uterine stimulant activity; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Bishop's Weed usually refers to Ammi majus, a flowering plant in the carrot family (Apiaceae). It grows in parts of Europe, the Middle East, North Africa, and other regions with mild climates. Its lacy white flower clusters look a lot like Queen Anne's lace, which is why one of its nicknames is "false Queen Anne's lace."

The name "Bishop's Weed" is also sometimes used for a different plant called goutweed (Aegopodium podagraria). This monograph focuses on Ammi majus, the plant most often connected with traditional herbal and skin treatments.

The seeds of Ammi majus contain natural compounds called psoralens (furanocoumarins). These compounds react with sunlight or ultraviolet light, which is the basis for their long history of use in treating skin pigment problems. The plant has also been used in folk medicine for digestive, breathing, and urinary complaints.

Uses & effectiveness

The most studied use of Ammi majus is for skin conditions, especially vitiligo (patches of skin that lose their color) and psoriasis. The plant's psoralen compounds are related to medicines used in a treatment called PUVA, which combines a psoralen drug with ultraviolet A light. This medical approach is a recognized therapy, but it uses purified, carefully dosed compounds under a doctor's care — not raw herb taken at home.

People have also traditionally used Bishop's Weed for digestive upset, asthma, angina (chest pain), kidney stones, and as a diuretic. The evidence for these uses is weak and comes mostly from traditional practice, laboratory studies, or animal research rather than good human trials.

Overall, there is not enough high-quality evidence to recommend Bishop's Weed as a self-care supplement for any condition. The skin benefits that have been studied depend on combining the active compounds with controlled light exposure, which needs medical supervision.

How it works

The main active compounds in Ammi majus seeds are psoralens, a type of furanocoumarin. When these compounds are in the skin and the skin is then exposed to ultraviolet light, they react and affect how skin cells behave. In vitiligo, this reaction is thought to help skin make pigment again. In psoriasis, it is thought to slow down the rapid growth of skin cells.

The plant also contains other compounds, including ones in the khellin family, that have been studied in the lab for relaxing smooth muscle, which is the idea behind its traditional use for breathing problems and spasms.

It is important to know that much of this understanding comes from laboratory and animal studies, or from purified drug versions of these compounds — not from the whole, raw herb taken by mouth.

Safety & precautions

Bishop's Weed should be treated with real caution. The psoralen compounds make the skin and eyes very sensitive to light. Touching the plant and then going into the sun can cause severe burns, blisters, and lasting skin discoloration — a reaction called phytophotodermatitis. Taking it internally can be toxic.

Because of these risks, you should not use Bishop's Weed on your own. Any psoralen-based treatment for skin conditions should be managed by a dermatologist who can control the dose and light exposure and watch for side effects.

Pregnancy: Avoid. There is not enough safety information, and the active compounds may be harmful. Breastfeeding: Avoid, since safety is unknown. People with liver problems, eye conditions, or a history of skin cancer should be especially careful and talk to a doctor first.

Side effects

The most common problems are skin-related: redness, burning, blistering, and long-lasting darkening of the skin, especially after sun or UV exposure. Eyes can also become very sensitive to light, and there is concern about eye damage such as cataracts with repeated psoralen-plus-light exposure.

Taken by mouth, the plant can cause nausea, stomach upset, and other signs of toxicity. Long-term or repeated psoralen-plus-UV treatment has also been linked to an increased risk of skin cancer over time.

If you develop a severe skin reaction, swelling, or trouble breathing, stop use and seek medical care right away.

Bishop's Weed: Reported Adverse Effects

Documented safety reports on Bishop's Weed from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

There is currently a limited amount of information available about the adverse effects of bishop's weed. Orally, bishop's weed has been reported to cause nausea, vomiting, and headache. Topically, bishop's weed may be photoreactive and phototoxic. It can also cause contact dermatitis.

Reports by condition

Cluster headache Neurologic/CNS

Orally, bishop's weed has been reported to cause headache.

Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.

Dermatitis Immunologic

Topically, bishop's weed can cause contact dermatitis. In one case report, a 31-year-old atopic female florist experienced IgE-mediated contact urticaria and rhinitis after exposure to bishop's weed.

Dermatitis Dermatologic

Topically, bishop's weed may be photoreactive and phototoxic due to its photoreactive furocoumarin constituents. Bishop's weed has caused photosensitization, phototoxic skin damage, and phototoxic dermatitis.

Nausea and vomiting Gastrointestinal

Orally, bishop's weed has been reported to cause nausea and vomiting.

Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no established, standardized over-the-counter dose for Bishop's Weed, and it is not recommended as a do-it-yourself supplement. Medical psoralen treatments use carefully measured, prescription-strength compounds combined with timed light therapy under a doctor's supervision.

If you come across a product containing Bishop's Weed or Ammi majus, follow the product label exactly and, more importantly, check with a pharmacist or doctor before using it. Do not increase the dose or combine it with sun or tanning beds on your own.

Pregnancy & Breastfeeding

Bishop's Weed & Pregnancy

Likely Unsafe

When used orally. Khellin, a constituent of bishop's weed, has uterine stimulant activity; avoid using.

Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

Bishop's Weed & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid using.

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 8 references that drive our Bishop's Weed monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
Kiistala R, Makinen-Kiljunen S, Heikkinen K, et al. Occupational allergic rhinitis and contact urticaria caused by bishop's weed (Ammi majus). Allergy 1999;54:635-9.
Ossenkoppele PM, van der Sluis WG, van Vloten WA. [Phototoxic dermatitis following the use of Ammi majus fruit for vitiligo]. Ned Tijdschr Geneeskd 1991;135:478-80.
Malhotra S, Bailey DG, Paine MF, Watkins PB. Seville orange juice-felodipine interaction: comparison with dilute grapefruit juice and involvement of furocoumarins. Clin Pharmacol Ther 2001;69:14-23. PubMed
Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.
Dr. Duke's Phytochemical and Ethnobotanical Databases. Available at: http://www.ars-grin.gov/duke/.
Dollahite, J. W., Younger, R. L., and Hoffman, G. O. Photosensitization in cattle and sheep caused by feeding Ammi majus (greater Ammi; Bishop's-Weed). Am J Vet.Res 1978;39(1):193-197. DOI
Kavli, G. and Volden, G. Phytophotodermatitis. Photodermatol. 1984;1(2):65-75.

Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

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.

Brand directory

Brands that make products with Bishop's Weed

18 brands in our database make a supplement containing Bishop's Weed.

Ayur Earth 21 products Ayurvedic Rasayanas 42 products Banyan Botanicals 697 products Botanica Boost 3 products EC Sports 3 products GNC Beyond Raw 212 products Harmony Nutraceuticals 47 products Hawaii Pharm 4,726 products Health Thru Nutrition 103 products Health Thru Nutrition Naturally 123 products Herbal Hills 425 products Herbal Shots 12 products Herbal Terra 3,138 products Herbal Zap! 4 products Himalaya 287 products MuscleTech Performance Series 202 products Nature's Sunshine 1,360 products R-U-Ved 46 products

Product directory

Supplement products with Bishop's Weed

83 products in our database contain Bishop's Weed. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Bishop's Weed: Common Questions

Does Bishop's Weed interact with prescription medications?

Yes. We list 954 medications with a known interaction with Bishop's Weed. Use the checker above to see how Bishop's Weed interacts with a specific drug.

How are Bishop's Weed interactions rated?

Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.

Is it safe to take Bishop's Weed with my medications?

It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.

Where does this Bishop's Weed interaction information come from?

Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.

What is Bishop's Weed used for?

It has been used mainly for skin conditions like vitiligo and psoriasis because its seeds contain light-sensitizing psoralen compounds. It has also been used traditionally for digestive, breathing, and urinary problems, though good evidence for these uses is lacking.

Is Bishop's Weed safe to take?

It is not considered safe for self-care. The plant can be toxic if swallowed and can cause severe skin and eye reactions when the skin is exposed to sunlight, so any use should be supervised by a doctor.

Can I use Bishop's Weed during pregnancy or while breastfeeding?

No. There is not enough safety information, and the active compounds may be harmful, so it should be avoided during pregnancy and breastfeeding.

Why does Bishop's Weed make my skin react to sunlight?

Its seeds contain psoralens, natural compounds that react with ultraviolet light. This can cause severe sunburn, blistering, and skin darkening, which is why sun protection and medical supervision are so important.

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

Keep exploring

Products that contain Bishop's Weed

A rotating sample of real supplements in our database that list Bishop's Weed — open any to see its full ingredients and every drug interaction we check.

See all 83 products with Bishop's Weed →

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