Drug & supplement interaction

Bishop's Weed + Famciclovir

Famciclovir brand name: Famvir.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between Bishop's Weed and Famciclovir in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Bishop's Weed and Famciclovir

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Famciclovir and Bishop's Weed in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Bishop's Weed safety at a glance

Bishop's Weed overall Use caution The plant contains light-sensitizing compounds and can be toxic; use only under medical supervision.
Pregnancy Likely Unsafe When used orally. Khellin, a constituent of bishop's weed, has uterine stimulant activity; avoid using. Read the full pregnancy detail
Breastfeeding Avoid Safety is unknown while breastfeeding, so it is best avoided.

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Famciclovir and Bishop's Weed? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Famciclovir

Interactions in our licensed database are recorded against drug classes, not just single drug names. Famciclovir is filed under a single classification — oral drugs. Bishop's Weed has documented interactions with 3 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate), cytochrome p450 3a4 (cyp3a4) substrates (moderate) and photosensitizing drugs (moderate) — and none of Famciclovir’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Bishop's Weed Does Interact With Other Medications

Bishop's Weed has 954 moderate known drug interactions in our database — Famciclovir isn’t one of them. If you take anything else, check it against the full list below.

Moderate 954 No known interaction 1,876 (incl. Famciclovir)
Taking anything else?

Check Another of Your Medications Against Bishop's Weed

Covers the 2,830 medications we’ve checked against Bishop's Weed. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Bishop's Weed and Famciclovir May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Hives Worth acting on Additional detail

    Bishop's Weed

    “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.”

    Bishop's Weed · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 2521. 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.
    2. 2520. 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.

    Famciclovir

    Listed in the ADVERSE REACTIONS section of the FDA label for Famciclovir. Read the label on DailyMed ›

  • A skin rash Additional detail

    Bishop's Weed

    “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.”

    Bishop's Weed · Natural Medicines adverse-effect record, reported in cluster headache.

    5 sources cited
    1. 7161. Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.
    2. 2520. 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.
    3. 2521. 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.
    4. 35679. 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
    5. 35680. Kavli, G. and Volden, G. Phytophotodermatitis. Photodermatol. 1984;1(2):65-75.

    Famciclovir

    Listed in the ADVERSE REACTIONS section of the FDA label for Famciclovir. Read the label on DailyMed ›

  • Vomiting / Nausea Additional detail

    Bishop's Weed

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

    Bishop's Weed · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 7161. Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.

    Famciclovir

    Listed in the ADVERSE REACTIONS section of the FDA label for Famciclovir. Read the label on DailyMed ›

  • Headache Additional detail

    Bishop's Weed

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

    Bishop's Weed · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 7161. Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.

    Famciclovir

    Listed in the ADVERSE REACTIONS section of the FDA label for Famciclovir. Read the label on DailyMed ›

Reported for Bishop's Weed but not commonly for Famciclovir: sun sensitivity and a stuffy or runny nose.

Effects for Famciclovir come from the ADVERSE REACTIONS section of its FDA label; effects for Bishop's Weed come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Bishop's Weed in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

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

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.© 2026 Therapeutic Research Center

From our Q&A

Questions About Bishop's Weed or Famciclovir

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Bishop's Weed or Famciclovir, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Famciclovir

This page covers Bishop's Weed only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Famciclovir page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Famciclovir page

“Famciclovir (Famvir) treats herpes infections like shingles and cold sores, and it only works if enough of the drug gets absorbed from your gut, which is exactly where every supplement on this list can interfere. The entry I would take most seriously is activated charcoal, the lone major-rated interaction, because charcoal binds medica…”

Reviewed by 2 · Jul 18, 2026

Open the Famciclovir interaction page

One more smart check

Taking Bishop's Weed as Part of a Dietary Supplement Product? Check It for Interactions

We hold 83 real supplement products containing Bishop's Weed, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bishop's Weed. Even though Bishop's Weed itself has no known interaction with Famciclovir, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Bishop's Weed and Famciclovir Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Bishop's Weed
Top half

#550 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Famciclovir
Top 25%

#634 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Bishop's Weed reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The Bishop's Weed and Famciclovir records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Bishop's Weed

What is Bishop's Weed?

Bishop's Weed
  • Vitiligo (loss of skin color)
  • Psoriasis
  • Digestive complaints
  • Asthma and breathing problems
  • Kidney stones
  • Diuretic (increasing urine)

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.

Ammi majus · Apiaceae · Seeds (fruit) and the extracted compounds (furanocoumarins) · Seed extracts, topical preparations, and isolated compounds (such as standardized psoralens used in some skin treatments)

An interaction check asks whether these two react with each other — it does not ask whether Bishop's Weed is a good idea for someone in your situation. Here is what our Bishop's Weed record says about it on its own.

Bishop's Weed: 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. Do not increase the dose or combine it with sun or tanning beds on your own.

From our Bishop's Weed monograph — the full record covers uses, side effects and every documented interaction.

Read the full Bishop's Weed monograph & all interactions
Medication

About Famciclovir

What Is Famciclovir Used For?

Brand name: Famvir

Famciclovir treats infections caused by herpes viruses in adults. It is used for recurrent cold sores (herpes labialis), recurrent genital herpes and shingles (herpes zoster).

It can also be used for suppressive therapy, which means daily treatment to help prevent recurrent genital herpes outbreaks. In adults with HIV, it treats recurrent episodes of cold sores around the mouth (orolabial herpes) or genital herpes.

See full Famciclovir drug information
Keep checking

Other Drugs & Bishop's Weed

Browse every other medication we’ve checked against Bishop's Weed — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
954Moderate
0Minor
1,875No known interaction
954 Moderate 1,875 No interaction
Moderate

954 interactions

Showing 60 of 954 moderate interactions — see all 954 on the Bishop's Weed page.

No interaction 1,875 drugs checked — show the list

We also checked Bishop's Weed against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,875 medications checked with no known interaction — see the full Bishop's Weed list.

See the full Bishop's Weed interactions page
See every supplement checked against Famciclovir, ranked by severity
Evidence & sources

Bishop's Weed References

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.

  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  2. 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.
  3. 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.
  4. 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
  5. Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.
  6. Dr. Duke's Phytochemical and Ethnobotanical Databases. Available at: http://www.ars-grin.gov/duke/.
  7. 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
  8. Kavli, G. and Volden, G. Phytophotodermatitis. Photodermatol. 1984;1(2):65-75.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Bishop's Weed and Famciclovir Together: Common Questions

Is it safe to take Bishop's Weed with Famciclovir?
We do not list a known interaction between Bishop's Weed and Famciclovir. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Bishop's Weed and Famciclovir have any of the same side effects?
Yes — our sources link each of them separately to 5 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Bishop's Weed and Famciclovir combination checked?
Interactions in our licensed database are recorded against drug classes. Famciclovir is filed under 1 classification, and Bishop's Weed has documented interactions with 3 drug classes — none of Famciclovir's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Bishop's Weed interact with any other medications?
Yes. Bishop's Weed has 954 documented drug interactions in our database — Famciclovir is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Famciclovir interact with any supplements?
Yes. Famciclovir has documented interactions with 17 supplements in our database — Bishop's Weed is not one of them. The Famciclovir interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Bishop's Weed monograph Uses, safety profile, and every drug interaction in one place Famciclovir drug information The full plain-English guide to this medication Famciclovir supplement interactions Every supplement checked against Famciclovir, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 8 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Famciclovir and Bishop's Weed?

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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.