Drug & supplement interaction

Rooibos + Macitentan

Macitentan brand name: Opsumit.

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

Rooibos has a moderate interaction with Macitentan. Theoretically, taking rooibos with CYP3A4 substrates may increase the effects of CYP3A4 substrates.

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

Rooibos and Macitentan

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Macitentan

Macitentan falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Rooibos interacts with.

Theoretically, taking rooibos with CYP3A4 substrates may increase the effects of CYP3A4 substrates.
In vitro research shows that the methanol extract of rooibos leaves and stems strongly inhibits CYP3A4 enzyme activity.
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

Your body clears macitentan (Opsumit) using a liver enzyme called CYP3A4. Lab studies hint that concentrated rooibos extract may slow this same enzyme down. If that happened, more macitentan could linger in your system, which might nudge up its usual effects, things like headache, low blood pressure, swelling in your legs, a stuffy nose, or feeling more tired or anemic.

Here's the reassuring part: this is only a theory based on test-tube work, not real people, and a normal cup of rooibos tea is very unlikely to cause trouble. Concentrated rooibos extract supplements are the bigger question mark. Before adding one, just run it by your pharmacist or doctor so they can keep an eye on things.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fantoukh OI, Dale OR, Parveen A, et al. Safety Assessment of Phytochemicals Derived from the Globalized South African Rooibos Tea (Aspalathus linearis) through Interaction with CYP, PXR, and P-gp. J Agric Food Chem. 2019;67(17):4967-4975.

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

Rooibos Also Interacts With Other Medications

Rooibos has 878 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 878 No known interaction 1,952 (incl. Macitentan)
Taking anything else?

Check Another of Your Medications Against Rooibos

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

Everything else you take

See Every Supplement That Interacts With Macitentan

This page covers Rooibos 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 Rooibos as Part of a Dietary Supplement Product? Check It for Interactions

We hold 142 real supplement products containing Rooibos, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Rooibos. Your product may carry other ingredients that interact with Macitentan too, on top of Rooibos — 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 Rooibos 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 Rooibos
Top half

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

29 days ago today
Medication Macitentan
Top 25%

#315 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 Rooibos

What is Rooibos?

Rooibos
  • Caffeine-free beverage
  • Antioxidant support
  • Heart health
  • Blood sugar support
  • Digestive upset
  • General wellness

Rooibos is a caffeine-free herbal tea from South Africa that is rich in antioxidants and generally considered safe as a beverage. While lab and early studies suggest possible benefits for heart health, blood sugar, and inflammation, strong human evidence is lacking for most medical uses. Enjoy it as a tea, but talk to your pharmacist or doctor before using concentrated extracts for health reasons.

Read the full Rooibos 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 & Rooibos

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

0Major
878Moderate
0Minor
1,951No known interaction
878 Moderate 1,951 No interaction
Moderate

878 interactions

Showing 60 of 878 moderate interactions — see all 878 on the Rooibos page.

No interaction 1,951 drugs checked — show the list

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

Showing the 60 most looked-up of 1,951 medications checked with no known interaction — see the full Rooibos list.

See the full Rooibos 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
Rooibos 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 Rooibos and Macitentan Together: Common Questions

Can you take Rooibos 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 Rooibos 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 Rooibos?

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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.