Drug & supplement interaction

Camphor + Macitentan

Macitentan brand name: Opsumit.

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

Camphor has a moderate interaction with Macitentan. 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 Macitentan

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Macitentan

Macitentan 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 gist with Opsumit (macitentan): it can be tough on the liver, which is why your doctor checks your liver enzymes before and during treatment. Camphor, the cooling ingredient in many rub-on muscle and chest products, has rarely been tied to brief bumps in liver enzymes too. So the worry is that stacking two things that may stress the liver could, in theory, add up.

I want to be honest about how shaky this is. This warning is theoretical, based on how these substances behave, plus a small handful of case reports. Used as directed on the skin, camphor is unlikely to cause real trouble. The real danger with camphor is swallowing it, which is toxic and should never be done. Before adding any camphor product, just run it by your pharmacist or doctor first.

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 Macitentan 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. Macitentan)
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.

Everything else you take

See Every Supplement That Interacts With Macitentan

This page covers Camphor only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Macitentan page lists 253 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Beer (major) and Grapefruit (major).

By severity: 9 major · 205 moderate · 39 minor.

From our pharmacist’s overview on the Macitentan page

“If you take macitentan (Opsumit) for pulmonary arterial hypertension, study this page rather than skim it. It lists 253 supplement and herbal ingredients, nine rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Macitentan 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 Macitentan 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 Macitentan 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

#1,390 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Macitentan
Top 5%

#88 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 Macitentan

What Is Macitentan Used For?

Brand name: Opsumit

Macitentan tablets — sold under the brand name Opsumit — are used to treat pulmonary arterial hypertension (PAH, WHO Group I), a serious condition where the blood pressure in the arteries supplying the lungs is abnormally high. The goal is to slow down how quickly the disease gets worse and to lower the chances of being hospitalized because of it.

In clinical studies, it was shown to be effective in adults with mostly moderate-to-severe PAH symptoms. Patients in those studies had PAH caused by unknown or inherited reasons, connective tissue disorders, or congenital heart disease with repaired heart shunts.

See full Macitentan 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 Macitentan, 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 Macitentan supplement interactions › Every supplement checked against Macitentan, ranked by severity Macitentan 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 Macitentan Together: Common Questions

Can you take Camphor with Macitentan?
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 Macitentan 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 Macitentan 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.