Drug & supplement interaction

Activated Charcoal + Ketoconazole

Ketoconazole brand name: Nizoral.

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

Activated Charcoal has a major interaction with Ketoconazole. Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Activated Charcoal and Ketoconazole

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

Major

ORAL DRUGS

Why this applies to Ketoconazole

Ketoconazole falls under ORAL DRUGS — the group Activated Charcoal interacts with.

Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.
Activated charcoal adsorbs various drugs and may reduce their absorption and/or half-life. Examples of affected drugs include acetaminophen, aminophylline, amiodarone, atenolol, carbamazepine, dapsone, digoxin, disopyramide, fluoxetine, indomethacin, moxifloxacin, nadolol, phenytoin, phenobarbital, piroxicam, quinine, sotalol, theophylline, tricyclic antidepressants, valproate, and verapamil. Avoid co-administration, except after drug overdose.
Severity Major Likelihood Probable Evidence B

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..

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

Here's the simple version: when you swallow activated charcoal, it acts like a sponge in your gut and grabs onto things sitting nearby, including your oral ketoconazole tablet. If charcoal soaks up the ketoconazole before your body can absorb it, less of the antifungal actually makes it into your bloodstream. That means a weaker effect, and your fungal infection may not clear the way it should.

The good news is this is mostly a timing issue, not a permanent ban. Charcoal can't bind a drug that's already been absorbed. So the concern is taking them close together. Don't change your ketoconazole on your own. Ask your pharmacist how to space them out, or whether to skip the charcoal entirely, since its everyday benefits are pretty unproven anyway.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Anon. Position statement and practice guidelines on the use of multi-dose activated charcoal in the treatment of acute poisoning. American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. J Toxicol Clin T
  2. Hoegberg LC, Angelo HR, Christophersen AB, Christensen HR. Effect of ethanol and pH on the adsorption of acetaminophen (paracetamol) to high surface activated charcoal, in vitro studies. J Toxicol Clin Toxicol 2002;40:59-67. PubMed
  3. Brahmi N, Kouraichi N, Thabet H, Amamou M. Influence of activated charcoal on the pharmacokinetics and the clinical features of carbamazepine poisoning. Am J Emerg Med 2006;24(4):440-3. PubMed
  4. Gude AB, Hoegberg LC, Angelo HR, Christensen HR. Dose-dependent adsorptive capacity of activated charcoal for gastrointestinal decontamination of a simulated paracetamol overdose in human volunteers. Basic Clin Pharmacol Toxicol 2010;106(5)406-10. PubMed
  5. Wananukul W, Klaikleun S, Sriapha C, Tongpoo A. Effect of activated charcoal in reducing paracetamol absorption at supra-therapeutic dose. J Med Assoc Thai 2010;93(10):1145-9.
  6. Wang X, Mondal S, Wang J, et al. Effect of activated charcoal on apixaban pharmacokinetics in healthy subjects. Am J Cardiovasc Drugs 2014;14(2):147-54. PubMed
  7. Chyka PA, Seger D, Krenzelok EP, et al. Position paper: single-dose activated charcoal. Clin Toxicol (Phila) 2005;43(2):61-87. PubMed
  8. Chiew AL, Gluud C, Brok J, Buckley NA. Interventions for paracetamol (acetaminophen) overdose. Cochrane Database Syst Rev 2018;2:CD003328. PubMed
  9. Skov K, Graudal NA, Jürgens G. The effect of activated charcoal on drug exposure following intravenous administration: A meta-analysis. Basic Clin Pharmacol Toxicol 2021;128(4):568-578. 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

Activated Charcoal Also Interacts With Other Medications

Activated Charcoal has 2,021 major, 5 moderate known drug interactions in our database — the Ketoconazole one above is one of them. If you take anything else, check it against the full list below.

Major 2,021 Moderate 5 No known interaction 804 (incl. Ketoconazole)
Taking anything else?

Check Another of Your Medications Against Activated Charcoal

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

From our Q&A

Questions About Activated Charcoal or Ketoconazole

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Activated Charcoal or Ketoconazole, 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 Ketoconazole

This page covers Activated Charcoal only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ketoconazole page lists 182 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Beer (major), Grapefruit (major), Siberian Cocklebur (major), St. John's Wort (major) and Wine (major).

By severity: 6 major · 135 moderate · 41 minor.

From our pharmacist’s overview on the Ketoconazole page

“Ketoconazole (Nizoral) is already hard on the liver, so treat its 182 interacting supplements with genuine care, starting with the six rated major. Most of the list runs through CYP3A4, the liver enzyme ketoconazole strongly blocks, so it can raise levels of over a hundred herbal ingredients, while grapefruit pushes ketoconazole itself…”

Reviewed by 2 · Jul 18, 2026

Open the Ketoconazole interaction page

One more smart check

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

We hold 256 real supplement products containing Activated Charcoal, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Activated Charcoal. Your product may carry other ingredients that interact with Ketoconazole too, on top of Activated Charcoal — 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 Activated Charcoal and Ketoconazole 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 Activated Charcoal
Top 25%

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

29 days ago today
Medication Ketoconazole
Steady interest

#1,878 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 Activated Charcoal

What is Activated Charcoal?

Activated Charcoal
  • Poisoning and drug overdose (in emergency care)
  • Gas and bloating
  • Upset stomach
  • Diarrhea
  • Teeth whitening
  • General 'detox'

Activated charcoal is a highly porous form of carbon that can bind certain substances in the gut, and it is used in hospitals to treat some poisonings and overdoses. For everyday uses like gas, bloating, detox, or teeth whitening, the evidence is weak or unclear. If you suspect a poisoning, call your local poison control center or seek emergency care first rather than using a home product.

Read the full Activated Charcoal monograph & all interactions
Medication

About Ketoconazole

What Is Ketoconazole Used For?

Brand name: Nizoral

Ketoconazole 2% shampoo and foam are used to treat tinea versicolor (also called pityriasis versicolor) — a fungal infection caused by Pityrosporum orbiculare (also known as Malassezia furfur), a yeast that naturally lives on the skin.

This infection creates light or dark patches, most often on the trunk, neck, arms, and upper thighs. Even after the fungus is cleared, those skin patches may take months to return to their normal color — that's normal, and depends on your skin type and sun exposure. Tinea versicolor can also come back, since the fungus lives on healthy skin even when there's no active infection.

See full Ketoconazole drug information
Keep checking

Other Drugs & Activated Charcoal

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

2,021Major
5Moderate
0Minor
803No known interaction
2,021 Major 5 Moderate 803 No interaction
Major

2,021 interactions

Showing 60 of 2,021 major interactions — see all 2,021 on the Activated Charcoal page.

Moderate

5 interactions

No interaction 803 drugs checked — show the list

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

Showing the 60 most looked-up of 803 medications checked with no known interaction — see the full Activated Charcoal list.

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

Can you take Activated Charcoal with Ketoconazole?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Activated Charcoal and Ketoconazole interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Ketoconazole and Activated Charcoal?

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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.