Drug & supplement interaction

Camphor + Isoniazid

Isoniazid brand names: Laniazid, INH, Nydrazid.

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

Camphor has a moderate interaction with Isoniazid. Theoretically, concomitant use of camphor with other hepatotoxic drugs might increase the risk of liver damage.

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

Camphor and Isoniazid

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Isoniazid

Isoniazid falls under HEPATOTOXIC DRUGS — the group Camphor interacts with.

Theoretically, concomitant use of camphor with other hepatotoxic drugs might increase the risk of liver damage.
There have been a few case reports of transient elevations in liver enzymes in adults after oral or topical use of camphor. There has also been one case of hepatotoxicity in an infant after topical camphor use.
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 know about isoniazid: it's already one of those TB medicines that can be tough on the liver. That's why your doctor checks your liver with blood tests while you're on it. Camphor, the cooling ingredient in many rub-on muscle and chest products, has been linked in a handful of case reports to temporary bumps in liver enzymes, even when used on the skin.

So the worry is simply this: stacking two things that can stress the liver. To be fair, this is a theoretical concern based on how camphor behaves, not a proven, common problem, and normal topical use is usually mild. Still, watch for warning signs like yellowing eyes or skin, dark urine, belly pain, nausea, or unusual tiredness, and run any camphor product past your pharmacist first. Never swallow camphor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Uc A, Bishop WP, Sanders KD. Camphor hepatotoxicity. South Med J 2000;93:596-8. DOI
  2. Rampini, S. K., Schneemann, M., Rentsch, K., and Bachli, E. B. Camphor intoxication after cao gio (coin rubbing). JAMA 7-3-2002;288(1):45.
  3. Cordoba Torres IT, Marino-Nieto J, Barkin HB, Fort AC, Cobas M. Vicks VapoRub intoxication: an unusual presentation of multiorgan failure. J Clin Anesth 2018;48:46-7. 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

Camphor Also Interacts With Other Medications

Camphor has 369 moderate known drug interactions in our database — the Isoniazid one above is one of them. If you take anything else, check it against the full list below.

Moderate 369 No known interaction 2,461 (incl. Isoniazid)
Taking anything else?

Check Another of Your Medications Against Camphor

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

From our Q&A

Questions About Camphor or Isoniazid

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

This page covers Camphor only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isoniazid page lists 84 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Adrafinil (moderate).

By severity: 4 major · 67 moderate · 13 minor.

From our pharmacist’s overview on the Isoniazid page

“The liver does most of the worrying here. Isoniazid, a backbone of tuberculosis treatment, is already hard on the liver by itself, and 38 of the supplements on this list can add strain, from Siberian cocklebur, a major-rated entry, to everyday herbs like ashwagandha and black cohosh.”

Reviewed by 2 · Jul 18, 2026

Open the Isoniazid interaction page

One more smart check

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

We hold 51 real supplement products containing Camphor, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Camphor. Your product may carry other ingredients that interact with Isoniazid too, on top of Camphor — 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 Camphor and Isoniazid 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 Camphor
Steady interest

#1,087 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Isoniazid
Steady interest

#1,791 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 Camphor

What is Camphor?

  • Muscle and joint aches
  • Cough and chest congestion
  • Itching and skin irritation
  • Cold sores or minor wounds
  • Counterirritant for pain

Camphor is a strong-smelling compound from the camphor tree (or made synthetically) that is used in many topical rub-on products for muscle aches, itching, and chest congestion. It can be helpful for these uses when applied to the skin in small, regulated amounts, but it is toxic and potentially deadly if swallowed, so it should never be taken by mouth. Keep camphor products away from children and check with a pharmacist before use.

Read the full Camphor monograph & all interactions
Medication

About Isoniazid

What Is Isoniazid Used For?

Brand names: Laniazid, INH, Nydrazid

Isoniazid is used to treat all forms of tuberculosis (TB) caused by susceptible bacteria. Because TB bacteria can quickly become resistant to a single drug, isoniazid must always be combined with other anti-TB medications when treating active TB — it is never used alone for active disease.

Isoniazid is also used as preventive therapy (sometimes called latent TB treatment) for people who have a positive TB skin test but do not yet have active disease. This includes people with HIV infection, close contacts of someone with active TB, recent TB skin test converters, and people with certain medical conditions — such as silicosis, diabetes mellitus, end-stage renal disease, leukemia, or Hodgkin's disease — that raise their TB risk.

See full Isoniazid drug information
Keep checking

Other Drugs & Camphor

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

0Major
369Moderate
0Minor
2,460No known interaction
369 Moderate 2,460 No interaction
Moderate

369 interactions

Showing 60 of 369 moderate interactions — see all 369 on the Camphor page.

No interaction 2,460 drugs checked — show the list

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

Showing the 60 most looked-up of 2,460 medications checked with no known interaction — see the full Camphor list.

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

Can you take Camphor with Isoniazid?
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 Camphor and Isoniazid 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 and Camphor?

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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.