Relugolix and Ketoconazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole Topical
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.
What happens
Increased relugolix exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Avoid concomitant use of relugolix (P-gp substrate) and P-gp inhibitors as it may increase relugolix exposure, which may increase the risk of adverse reactions. If coadministration is unavoidable, administer relugolix-containing medication first, separate dosing by at least 6 hours, and monitor for adverse reactions more frequently12. Treatment with relugolix may be interrupted for up to 2 weeks for a short course of treatment with P-gp inhibitors. Resume relugolix after P-gp inhibitor is discontinued. If treatment with relugolix is interrupted for greater than 7 days, restart relugolix with a loading dose of 360 mg on the first day and continue with a dose of 120 mg once daily 1. Coadministration of relugolix with QT interval prolonging drugs may cause additive effects on the QT interval. Consider whether the benefits of androgen deprivation therapy, like relugolix outweigh the potential risks in patients with congenital long QT syndrome, congestive heart failure, or frequent electrolyte abnormalities and in patients taking drugs known to prolong the QT interval. Correct electrolyte abnormalities and consider periodic monitoring of ECGs and electrolytes 1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of relugolix; additive QT interval prolongation
Literature reports
1 report — tap to read
a) Coadministration of relugolix (P-gp substrate) with erythromycin (P-gp CYP3A inhibitor) increased the AUC and Cmax of relugolix by 3.5-fold and 2.9-fold, respectively 1.
Common questions
Can I take Relugolix and Ketoconazole Topical together?
Increased relugolix exposure and an increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Ketoconazole Topical 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 strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Relugolix or Ketoconazole Topical 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 Ketoconazole Topical
Keep reading about Relugolix
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