Carbamazepine and Relugolix: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Carbamazepine
Relugolix
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Carbamazepine can make relugolix (Orgovyx) work less well. Carbamazepine is a strong "speed-up" drug for your body's drug-clearing systems. When it speeds things up, your body clears relugolix faster, so less of it stays in your blood. That means relugolix may not do its job as well as it should.
This matters because relugolix is used for serious conditions where you really need it working. The good news is your care team can handle this. Do not stop or change either medicine on your own. Just let your pharmacist or doctor know you take both, and they can adjust your plan to keep you protected.
Effect: Reduced relugolix exposure and possible loss of efficacy.
Mechanism: Carbamazepine is a combined P-gp and strong CYP3A inducer. Relugolix is a P-gp and CYP3A substrate (not a prodrug), so induction increases its efflux and metabolism, lowering AUC and Cmax.
- Direction: Reduced relugolix effect.
- Magnitude: By analogy to rifampin, AUC decreased ~55% and Cmax ~23%.
- Evidence: Theoretical (extrapolated from rifampin data).
- Management: Avoid the combination. If unavoidable, increase relugolix to 240 mg once daily; resume 120 mg once daily after the inducer is stopped.
What happens
Reduced relugolix exposure and reduced efficacy of relugolix
Interaction Deep Dive
When relugolix, which is a substrate of both P-gp and CYP3A, is given together with an agent that induces both P-gp and CYP3A strongly, relugolix exposure falls and its effectiveness may be diminished. For this reason, relugolix or the relugolix/estradiol/norethindrone acetate combination should not be used alongside an agent that acts as a combined P-gp and strong CYP3A inducer12. In a case involving rifAMPin, which is a P-gp and strong CYP3A inducer, concurrent administration lowered relugolix AUC by 55% and Cmax by 23%. Should such coadministration be unavoidable, the relugolix dose should be raised to 240 mg once daily. Once the combined P-gp and strong CYP3A inducer has been stopped, return to the standard relugolix dose of 120 mg once daily1.
Why it happens (mechanism)
Induction of P-gp-mediated efflux transport of relugolix; induction of CYP3A-mediated metabolism of relugolix
How to manage this interaction
What your care team may do:
- Prefer to avoid using these two together when possible, or choose an alternative.
- If both are truly needed, the relugolix dose may be increased (to 240 mg once daily per labeling) and then returned to the usual 120 mg once daily after carbamazepine is stopped.
- Monitor you more closely to be sure relugolix is still working.
What you should do: Keep taking both exactly as prescribed and do not adjust anything yourself. Tell your pharmacist or prescriber that you take both drugs so they can tailor your dose and monitoring.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) When relugolix (a substrate of both P-gp and CYP3A) was given together with rifAMPin (an inducer of P-gp and a strong CYP3A inducer), the AUC and Cmax of relugolix were reduced by 55% and 23%, respectively 1.
Common questions
Can I take Carbamazepine and Relugolix together?
Carbamazepine can lower relugolix levels and weaken its effect, so this combination is best avoided; if both are needed your doctor may raise the relugolix dose and monitor you. Talk to your pharmacist or prescriber before changing anything. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Carbamazepine and Relugolix interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Carbamazepine and Relugolix interaction managed?
What your care team may do: Prefer to avoid using these two together when possible, or choose an alternative. If both are truly needed, the relugolix dose may be increased (to 240 mg once daily per labeling) and then returned to the usual 120 mg once daily after carbamazepine is stopped. Monitor you more closely to be sure relugolix is still working. What you should do: Keep taking both exactly as… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Carbamazepine or Relugolix need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: ORGOVYX oral tablets, relugolix oral tablets. Sumitomo Pharma America, Inc (per FDA), Marlborough, MA, 2025. DailyMed
- Product Information: MYFEMBREE(R) oral tablets, relugolix, estradiol, norethindrone acetate oral tablets. Myovant Sciences Inc (per FDA), Brisbane, CA, 2021. DailyMed
Keep reading about Carbamazepine
Keep reading about Relugolix
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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