Asunaprevir 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
Relugolix
Asunaprevir
No brand names on record
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.
Here's what's going on. Relugolix (Orgovyx) is cleared from your body partly by a pump in your gut called P-gp. Asunaprevir can block that pump. When the pump is blocked, more relugolix stays in your body than intended, so its side effects (like hot flashes, fatigue, or hormone-related effects) can become stronger.
The good news is that this is very manageable. Your care team may space the two medicines apart, watch you a bit more closely, or adjust your plan. Please don't stop or change either medicine on your own. Just check in with your pharmacist or doctor so they can set things up safely for you.
Mechanism: Asunaprevir inhibits P-glycoprotein (P-gp), reducing efflux of relugolix, a P-gp substrate. Neither drug is a prodrug, so the result is increased relugolix exposure and greater risk of relugolix-associated adverse effects.
Magnitude: As a reference, erythromycin (P-gp inhibitor) raised relugolix AUC ~3.5-fold and Cmax ~2.9-fold. Evidence: probable; onset unspecified.
Management:
- Avoid concomitant use when possible.
- If unavoidable, give relugolix first and separate dosing by at least 6 hours; monitor adverse reactions more frequently.
- Relugolix may be interrupted up to 2 weeks for short P-gp inhibitor courses; if interrupted >7 days, restart with a 360 mg loading dose then 120 mg daily.
What happens
Increased relugolix exposure
Interaction Deep Dive
Concurrent administration of relugolix (a P-gp substrate) with P-gp inhibitors should be avoided, since it can raise relugolix exposure and thereby heighten the likelihood of adverse reactions linked to relugolix. When coadministration cannot be prevented, give relugolix or relugolix/estradiol/norethindrone acetate first, allow a gap of at least 6 hours between doses, and increase the frequency of monitoring for adverse reactions12. For a brief course of certain P-gp inhibitors, relugolix therapy may be paused for as long as 2 weeks. Once the P-gp inhibitor has been stopped, relugolix can be resumed. Should the relugolix interruption exceed 7 days, reinitiate relugolix using a 360 mg loading dose on day one, followed by 120 mg once daily thereafter. In a drug interaction study, giving relugolix (P-gp substrate) together with erythromycin (P-gp inhibitor) raised the AUC and Cmax of relugolix by 3.5-fold and 2.9-fold, respectively1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of relugolix
How to manage this interaction
Taking both is usually avoided, but your care team can manage it if needed. Keep taking both exactly as prescribed unless your prescriber tells you otherwise.
- Your team may separate the doses (taking relugolix first, then spacing by at least 6 hours).
- They may monitor you more closely for relugolix side effects.
- In some cases, relugolix can be paused for a short course of the other drug, then restarted (sometimes with a loading dose) under your doctor's direction.
What to do: Ask your pharmacist or prescriber before combining these, and report any new or worsening side effects promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) During a drug interaction study, giving relugolix (a P-gp substrate) together with erythromycin (a P-gp inhibitor) raised relugolix AUC by 3.5-fold and Cmax by 2.9-fold 1.
Common questions
Can I take Asunaprevir and Relugolix together?
Asunaprevir can raise relugolix levels and its side effects by blocking a gut transporter, so this combination is generally avoided. Talk to your pharmacist or doctor, who can separate dosing, monitor you closely, or adjust your plan. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Asunaprevir 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 Asunaprevir and Relugolix interaction managed?
Taking both is usually avoided, but your care team can manage it if needed. Keep taking both exactly as prescribed unless your prescriber tells you otherwise. Your team may separate the doses (taking relugolix first, then spacing by at least 6 hours). They may monitor you more closely for relugolix side effects. In some cases, relugolix can be paused for a short course of the other drug, then rest… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Asunaprevir 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 Relugolix
Keep reading about Asunaprevir
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