Drug & supplement interaction

Coltsfoot + Griseofulvin

Griseofulvin brand names: Fulvicin PG, Fulvicin-U/F, Grisactin Ultra, Grisactin.

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

Coltsfoot has a moderate interaction with Griseofulvin. Hepatotoxic pyrrolizidine alkaloids (PA) are substrates of cytochrome P450 3A4 (CYP3A4).

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

Coltsfoot and Griseofulvin

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INDUCERS

Why this applies to Griseofulvin

Griseofulvin falls under CYTOCHROME P450 3A4 (CYP3A4) INDUCERS — the group Coltsfoot interacts with.

Hepatotoxic pyrrolizidine alkaloids (PA) are substrates of cytochrome P450 3A4 (CYP3A4). Theoretically, drugs that induce CYP3A4 might increase the conversion of PAs to toxic metabolites. Some drugs that induce CYP3A4 include carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin), rifampin, rifabutin (Mycobutin), and others.
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 thing to understand about pairing coltsfoot with griseofulvin. Coltsfoot can contain pyrrolizidine alkaloids (PAs), plant compounds that are already known to be hard on the liver. Your body uses an enzyme called CYP3A4 to handle these PAs, and that same enzyme is the one griseofulvin tends to speed up. The worry is that a faster enzyme could turn more of those PAs into the harmful, liver-toxic byproducts.

So this isn't really about griseofulvin working too weakly or too strongly. It's about possibly putting extra strain on your liver. I'll be honest with you though: this concern is theoretical and comes from lab and animal studies, not human evidence. Even so, coltsfoot is one I'd steer clear of unless it's certified PA-free. Please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46. PubMed
  2. Wang YP, Yan J, Fu PP, Chou MW. Human liver microsomal reduction of pyrrolizidine alkaloid N-oxides to form the corresponding carcinogenic parent alkaloid. Toxicol Lett 2005;155:411-20. 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

Coltsfoot Also Interacts With Other Medications

Coltsfoot has 373 moderate known drug interactions in our database — the Griseofulvin one above is one of them. If you take anything else, check it against the full list below.

Moderate 373 No known interaction 2,457 (incl. Griseofulvin)
Taking anything else?

Check Another of Your Medications Against Coltsfoot

Covers the 2,830 medications we’ve checked against Coltsfoot. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Griseofulvin

This page covers Coltsfoot only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Griseofulvin page lists 61 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alfalfa (moderate), Alkanna (moderate), Alpine Ragwort (moderate) and Angelica Archangelica (moderate).

By severity: 1 major · 47 moderate · 13 minor.

From our pharmacist’s overview on the Griseofulvin page

“If you take griseofulvin for a fungal infection of the skin, scalp, or nails, give this list of 61 ingredients real attention. The single major entry is activated charcoal, which binds the drug in your gut so less of it reaches your blood and the infection gets less treatment.”

Reviewed by 2 · Jul 18, 2026

Open the Griseofulvin interaction page

One more smart check

Taking Coltsfoot as Part of a Dietary Supplement Product? Check It for Interactions

We hold 60 real supplement products containing Coltsfoot, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Coltsfoot. Your product may carry other ingredients that interact with Griseofulvin too, on top of Coltsfoot — 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 Coltsfoot and Griseofulvin 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 Coltsfoot
Steady interest

#1,106 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Griseofulvin
Steady interest

#2,564 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 Coltsfoot

What is Coltsfoot?

Coltsfoot
  • Cough
  • Sore throat
  • Bronchitis and congestion
  • Loosening mucus (expectorant)
  • Asthma symptoms

Coltsfoot is a traditional herb long used to soothe coughs and clear mucus, but solid human evidence for these uses is lacking. More importantly, the raw plant can contain liver-toxic pyrrolizidine alkaloids, so it carries real safety concerns and is best avoided unless you use a product certified to be free of these compounds.

Read the full Coltsfoot monograph & all interactions
Medication

About Griseofulvin

What Is Griseofulvin Used For?

Brand names: Fulvicin PG, Fulvicin-U/F, Grisactin Ultra, Grisactin

Griseofulvin treats dermatophyte (ringworm-type) fungal infections of the skin, hair, and nails that haven't cleared up with topical (cream or ointment) treatment alone. It is used for tinea corporis (ringworm of the body), tinea pedis (athlete's foot), tinea cruris (jock itch), tinea barbae (ringworm of the beard area), tinea capitis (ringworm of the scalp), and tinea unguium (fungal nail infection).

It only works against specific dermatophyte fungi. Griseofulvin does not treat bacterial infections, yeast infections (candidiasis), or other fungal infections such as histoplasmosis, sporotrichosis, or tinea versicolor. A lab test or fungal culture should confirm the infection before treatment starts.

See full Griseofulvin drug information
Keep checking

Other Drugs & Coltsfoot

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

0Major
373Moderate
0Minor
2,456No known interaction
373 Moderate 2,456 No interaction
Moderate

373 interactions

Showing 60 of 373 moderate interactions — see all 373 on the Coltsfoot page.

No interaction 2,456 drugs checked — show the list

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

Showing the 60 most looked-up of 2,456 medications checked with no known interaction — see the full Coltsfoot list.

See the full Coltsfoot interactions page
See every supplement checked against Griseofulvin, 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
Coltsfoot monograph › Uses, safety, and every drug interaction in one place Griseofulvin supplement interactions › Every supplement checked against Griseofulvin, ranked by severity Griseofulvin 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 Coltsfoot and Griseofulvin Together: Common Questions

Can you take Coltsfoot with Griseofulvin?
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.
How serious is the Coltsfoot and Griseofulvin 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 Griseofulvin and Coltsfoot?

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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.