Drug & supplement interaction

Vitamin A + Isoniazid, Rifampin

Isoniazid, Rifampin brand name: Rifamate.

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

Vitamin A has a moderate interaction with Isoniazid, Rifampin. Theoretically, taking high doses of vitamin A in combination with other potentially hepatotoxic drugs might increase the risk of liver disease.

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

Vitamin A and Isoniazid, Rifampin

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Isoniazid, Rifampin

Isoniazid, Rifampin falls under HEPATOTOXIC DRUGS — the group Vitamin A interacts with.

Theoretically, taking high doses of vitamin A in combination with other potentially hepatotoxic drugs might increase the risk of liver disease.
The tolerable upper intake level (UL) is the highest level of intake that is likely to pose no risk of adverse effects. Doses of vitamin A above the UL can cause hepatotoxicity, ranging from elevated liver enzymes to liver failure.
Severity Moderate Likelihood Possible Evidence C

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 concern with this combo. Rifamate combines isoniazid and rifampin, two tuberculosis medicines that are already known to be tough on the liver. High doses of vitamin A can also stress the liver on their own. Stack them together and, at least in theory, you may add to the strain. To be clear, this is based on expert opinion rather than strong studies, so I don't want to alarm you.

What I'd watch for are signs of liver trouble: yellowing of the eyes or skin, dark urine, belly pain, nausea, or unusual tiredness. Normal food and a standard multivitamin almost never reach risky vitamin A levels, so the worry is really about high-dose supplements. Please check with your pharmacist or doctor before adding one.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  2. Fritz, H., Kennedy, D., Fergusson, D., Fernandes, R., Doucette, S., Cooley, K., Seely, A., Sagar, S., Wong, R., and Seely, D. Vitamin A and retinoid derivatives for lung cancer: a systematic review and meta analysis. PLoS.One. 2011;6(6):e21107. 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

Vitamin A Also Interacts With Other Medications

Vitamin A has 9 major, 377 moderate known drug interactions in our database — the Isoniazid, Rifampin one above is one of them. If you take anything else, check it against the full list below.

Major 9 Moderate 377 No known interaction 2,444 (incl. Isoniazid, Rifampin)
Taking anything else?

Check Another of Your Medications Against Vitamin A

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

From our Q&A

Questions About Vitamin A or Isoniazid, Rifampin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Vitamin A or Isoniazid, Rifampin, 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 Isoniazid, Rifampin

This page covers Vitamin A only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isoniazid, Rifampin page lists 145 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Apple (major), Asarabacca (major), Beer (major) and Grapefruit (major).

By severity: 8 major · 117 moderate · 20 minor.

From our pharmacist’s overview on the Isoniazid, Rifampin page

“Rifamate combines isoniazid and rifampin, the backbone of tuberculosis treatment, and both drugs are hard on the liver, which is why this list of 145 supplement and herbal interactions deserves genuine respect. Eight entries rate major, and the largest cluster, 38 ingredients, adds to that same liver strain, with alcohol in beer or win…”

Reviewed by 2 · Jul 18, 2026

Open the Isoniazid, Rifampin interaction page

One more smart check

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

We hold 19,215 real supplement products containing Vitamin A, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Vitamin A. Your product may carry other ingredients that interact with Isoniazid, Rifampin too, on top of Vitamin A — 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 Vitamin A and Isoniazid, Rifampin 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 Vitamin A
Top 1%

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

29 days ago today
Medication Isoniazid, Rifampin
Top 5%

#111 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 Vitamin A

What is Vitamin A?

  • Eye and vision health
  • Skin health and acne
  • Immune support
  • Correcting vitamin A deficiency
  • Childhood growth and development

Vitamin A is an essential nutrient important for vision, skin, immune function, and growth. Most people get enough from a balanced diet, and supplements are mainly useful for correcting a true deficiency. Because vitamin A is fat-soluble and can build up to harmful levels, more is not better, and high doses are especially risky in pregnancy.

Read the full Vitamin A monograph & all interactions
Keep checking

Other Drugs & Vitamin A

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

9Major
377Moderate
0Minor
2,443No known interaction
9 Major 377 Moderate 2,443 No interaction
Major

9 interactions

Moderate

377 interactions

Showing 60 of 377 moderate interactions — see all 377 on the Vitamin A page.

No interaction 2,443 drugs checked — show the list

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

Showing the 60 most looked-up of 2,443 medications checked with no known interaction — see the full Vitamin A list.

See the full Vitamin A interactions page
See every supplement checked against Isoniazid, Rifampin, 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
Vitamin A monograph › Uses, safety, and every drug interaction in one place Isoniazid, Rifampin supplement interactions › Every supplement checked against Isoniazid, Rifampin, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Vitamin A and Isoniazid, Rifampin Together: Common Questions

Can you take Vitamin A with Isoniazid, Rifampin?
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 Vitamin A and Isoniazid, Rifampin 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 Isoniazid, Rifampin and Vitamin A?

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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.