Drug & supplement interaction

Bishop's Weed + Dexchlorpheniramine

Dexchlorpheniramine brand names: Polaramine, Polaramine Repetabs.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Dexchlorpheniramine falls into 2 drug categories that Bishop's Weed can interact with; the most serious is rated moderate. Bishop's weed constituents seem to cause photosensitivity.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Bishop's Weed and Dexchlorpheniramine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Bishop's Weed interacts with whole categories of medication. Dexchlorpheniramine falls into 2 of those categories, so it can interact with Bishop's Weed in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

PHOTOSENSITIZING DRUGS

1 of 2

Why this applies to Dexchlorpheniramine

Dexchlorpheniramine falls under PHOTOSENSITIZING DRUGS — the group Bishop's Weed interacts with.

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.
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version. Bishop's Weed contains psoralens, which are natural compounds that make your skin much more sensitive to sunlight. Dexchlorpheniramine (Polaramine), the antihistamine you take for allergy or cold symptoms, can also make some people more prone to sunburn. Put the two together and the worry is an added effect, meaning your skin could burn faster than usual, even on a cloudy day.

I want to be straight with you though: this is mostly a theoretical concern backed only by anecdotal reports, not strong studies. Dexchlorpheniramine isn't activated by anything Bishop's Weed touches, so this isn't about the drug building up or stopping working. If you do use both, be smart about sun protection (sunscreen, hat, shade) and check in with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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. Dr. Duke's Phytochemical and Ethnobotanical Databases. Available at: http://www.ars-grin.gov/duke/.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Dexchlorpheniramine also falls under 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.
Severity Moderate Likelihood Possible Evidence B

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with these two together. Your body uses a liver enzyme called CYP3A4 to help clear dexchlorpheniramine (Polaramine). Bishop's Weed contains a compound called bergapten that can slow that enzyme down. If the enzyme works slower, more of the antihistamine can hang around in your blood than usual.

For dexchlorpheniramine, that would mean its typical effects get stronger. Think more drowsiness, a dry mouth, blurry vision, dizziness, or feeling foggy. It's worth noting this is mostly a theoretical concern based on lab data, not strong human studies, so I wouldn't panic. Still, since Bishop's Weed can be genuinely toxic on its own, please don't self-treat with it. Run any plans by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Bishop's Weed Also Interacts With Other Medications

Bishop's Weed has 953 moderate known drug interactions in our database — the Dexchlorpheniramine one above is among them. If you take anything else, check it against the full list below.

Moderate 953 No known interaction 1,877 (incl. Dexchlorpheniramine)
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.

From our Q&A

Questions About Bishop's Weed or Dexchlorpheniramine

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 Dexchlorpheniramine, 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 Dexchlorpheniramine

This page covers Bishop's Weed only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dexchlorpheniramine page lists 198 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), Henbane (major), Lithium (major) and Scopolia (major).

By severity: 6 major · 149 moderate · 43 minor.

From our pharmacist’s overview on the Dexchlorpheniramine page

“An allergy antihistamine like dexchlorpheniramine (Polaramine) sounds mild, but its interaction list warrants genuine care, and six of the 198 entries carry a major rating. The biggest cluster, 121 ingredients, can raise or lower the drug's blood levels through the liver enzyme that breaks it down.”

Reviewed by 2 · Jul 18, 2026

Open the Dexchlorpheniramine 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. Your product may carry other ingredients that interact with Dexchlorpheniramine too, on top of Bishop's Weed — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Bishop's Weed and Dexchlorpheniramine 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 25%

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

29 days ago today
Medication Dexchlorpheniramine
Top half

#1,122 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.

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.

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

About Chlorpheniramine

What Is Chlorpheniramine Used For?

Brand names: Polaramine, Polaramine Repetabs

Chlorpheniramine is used to temporarily relieve common allergy symptoms caused by hay fever (allergic rhinitis) or other upper respiratory allergies. These include runny nose, sneezing, itchy or watery eyes, and itching of the nose or throat.

These uses are supported across multiple products — including tablets (such as Aller-chlor, Allergy, Allergy Relief, Allergy Time, Anti Allergy, and Chlorpheniramine Maleate), extended-release tablets (Allergy Relief and Chlorphen-12), the oral solution Ed Chlorped Jr, and the inhalers ClorRelief and ClorRelief KIDs.

See full Chlorpheniramine 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
953Moderate
0Minor
1,876No known interaction
953 Moderate 1,876 No interaction
Moderate

953 interactions

Showing 60 of 953 moderate interactions — see all 953 on the Bishop's Weed page.

No interaction 1,876 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 1,876 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 Dexchlorpheniramine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

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

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

Keep exploring
Bishop's Weed monograph › Uses, safety, and every drug interaction in one place Dexchlorpheniramine supplement interactions › Every supplement checked against Dexchlorpheniramine, ranked by severity Chlorpheniramine drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Bishop's Weed and Dexchlorpheniramine Together: Common Questions

Can you take Bishop's Weed with Dexchlorpheniramine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Bishop's Weed and Dexchlorpheniramine?
Dexchlorpheniramine belongs to more than one drug category, and Bishop's Weed interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Bishop's Weed and Dexchlorpheniramine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Dexchlorpheniramine 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.