Clofazimine 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
Clofazimine
No brand names on recordRelugolix
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.
You've been prescribed clofazimine and relugolix (Orgovyx) together. Both of these medicines can affect the timing of your heartbeat, something doctors call the QT interval. When two drugs that do this are taken together, the effect can add up and, in rare cases, lead to an irregular heartbeat.
The good news is that this is a possible risk, not a sure thing, and your care team knows how to keep an eye on it. They may check your heart rhythm with an EKG and look at blood levels like potassium and magnesium. Please keep taking both as prescribed, and talk with your pharmacist or doctor if you feel dizzy, faint, or notice a fluttering heartbeat.
Effect: Additive QT interval prolongation with concurrent clofazimine and relugolix.
Mechanism: Both agents independently prolong cardiac repolarization; clofazimine is a known QT-prolonging drug, and androgen deprivation from relugolix (a GnRH antagonist) may also prolong QT. The effect is pharmacodynamic (additive), not metabolic. Neither is a prodrug relevant here.
Evidence: Theoretical; severity major; onset unspecified.
Management:
- Weigh benefit of androgen deprivation therapy vs risk, especially in congenital long QT, CHF, or recurrent electrolyte disturbances.
- Avoid combination when feasible; if required, correct and maintain normal K+ and Mg2+.
- Periodic ECG and electrolyte monitoring.
What happens
Increased risk of QT interval prolongation
Interaction Deep Dive
When relugolix is given together with medications that prolong the QT interval, the effects on the QT interval are additive. The androgen deprivation produced by GnRH agonists and antagonists may itself lengthen the QT interval. In patients who have congenital long QT syndrome, congestive heart failure, or recurrent electrolyte disturbances, as well as in those receiving drugs recognized to prolong the QT interval, weigh whether the benefits of androgen deprivation therapy such as relugolix outweigh the possible risks1. Where feasible, do not use relugolix concurrently with QT prolonging agents. Should coadministration be necessary, avoid agents that produce electrolyte disturbances (that is, hypokalemia or hypomagnesemia)2, correct any electrolyte disturbances, and consider periodic monitoring of ECGs and electrolytes1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Your care team can manage this safely. Here is what they typically do:
- Weigh the benefits and risks, particularly if you have a heart rhythm condition, heart failure, or a history of low potassium or magnesium.
- Monitor more closely with periodic EKGs and blood tests to check your electrolytes.
- Correct any low potassium or magnesium and avoid other things that lower them.
Keep taking both medicines exactly as prescribed. Do not stop either one on your own. Ask your pharmacist or prescriber before adding new medicines, and report any fainting, dizziness, or palpitations right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In an analysis of male patients on androgen deprivation therapy (ADT) using individual case safety reports from VigiBase, the international pharmacovigilance database, investigators identified 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% of which were fatal), along with 99 cases of sudden death linked to ADT. The majority of aLQTS/TdP cases (62%) and sudden death cases (88%) tied to ADT arose without concurrent use of other agents recognized to elevate TdP risk; nonetheless, use of 1 drug and 2 or more drugs carrying conditional, possible, or known TdP risk was documented in a portion of aLQTS/TdP (23% or 43%) and sudden death (18% and 22%) events. Agents classified as ADTs included abiraterone, gonadotropin-releasing hormone agonists and antagonists, nonsteroidal androgen receptor inhibitors approved for prostate cancer, and 5-alpha-reductase inhibitors approved for androgenic alopecia and prostatism. Among the 10 ADTs assessed, 7 showed a disproportional association (reporting odds ratio, 1.4 to 4.7) with aLQTS, TdP, or sudden death, namely leuprorelin, goserelin, triptorelin, degarelix, bicalutamide, finasteride, and dutasteride. The median patient age was approximately 76 years, and the median time to onset was 170 days (range, 7 to 4884 days) for aLQTS/TdP events and 92 days (range, 0.25 to 4984 days) for sudden death events. Patients were taking ADT mainly for prostate cancer, with some using it for prostatism and androgenic alopecia. Most patients were on ADT monotherapy (83%); 17% were receiving ADT combination therapy 3.
Common questions
Can I take Clofazimine and Relugolix together?
Combining clofazimine and relugolix can add up to prolong the QT interval, so your team may monitor your heart rhythm and electrolytes. Keep taking both as prescribed and report any fainting or palpitations. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Clofazimine 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 Clofazimine and Relugolix interaction managed?
Your care team can manage this safely. Here is what they typically do: Weigh the benefits and risks, particularly if you have a heart rhythm condition, heart failure, or a history of low potassium or magnesium. Monitor more closely with periodic EKGs and blood tests to check your electrolytes. Correct any low potassium or magnesium and avoid other things that lower them. Keep taking both medicines… 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.
Questions for your pharmacist
- Does my dose of Clofazimine 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 (3)
- Product Information: ORGOVYX oral tablets, relugolix oral tablets. Sumitomo Pharma America, Inc (per FDA), Marlborough, MA, 2025. DailyMed
- Lyon AR, Lopez-Fernandez T, Couch LS, et al: 2022 ESC guidelines on cardio-oncology developed in collaboration with the European Hematology Association (EHA), the European Society for Therapeutic Radiology and Oncology (ESTRO) and the International Cardio-Oncology Society (IC-OS). Eur Heart J 2022; 43(41):4229-4361.
- Salem JE, Yang T, Moslehi JJ, et al: Androgenic effects on ventricular repolarization: a translational study from the international pharmacovigilance database to iPSC-cardiomyocytes. Circulation 2019; 140(13):1070-1080. PubMed
Keep reading about Clofazimine
Keep reading about Relugolix
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