Relugolix and Efavirenz: 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
Efavirenz
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.
Both of these medicines can affect the timing of your heartbeat, something doctors measure on an ECG as the QT interval. Efavirenz (an HIV medicine) and relugolix (Orgovyx, used for prostate cancer) can each stretch out that interval a little. Taken together, those effects can add up, which in rare cases could lead to an irregular heartbeat.
The good news is this is a known, manageable concern. Your care team can check your ECG and blood minerals like potassium and magnesium, and weigh whether both drugs are truly needed. Please don't stop either one on your own. Just talk with your doctor or pharmacist so they can keep an eye on things.
Effect: Additive QT interval prolongation with combined efavirenz and relugolix. Both agents are independently associated with QTc prolongation; androgen deprivation therapy itself can prolong QT.
- Mechanism: Pharmacodynamic (additive QT effect), not a PK/enzyme interaction.
- Direction: Increased QT prolongation / torsades risk. Neither is a prodrug here.
- Evidence: Theoretical; severity major; onset unspecified.
- Management: Avoid combination when possible. If required, correct and maintain K+ and Mg2+, avoid other QT-prolonging or electrolyte-depleting agents, and obtain periodic ECG and electrolyte monitoring. Extra caution with congenital long QT, CHF, or bradyarrhythmia.
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 or antagonists can 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 are greater than the possible risks 1. Where feasible, do not use relugolix at the same time as QT prolonging agents. When coadministration cannot be avoided, refrain from using drugs that produce electrolyte disturbances (that is, hypokalemia or hypomagnesemia) 2, correct any electrolyte abnormalities, and consider periodic monitoring of ECGs and electrolytes 1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
This combination can add to QT prolongation, so your care team manages it by keeping a close watch rather than leaving it to chance.
- Keep taking both as prescribed unless your doctor tells you otherwise.
- Your team may weigh whether the benefits of therapy outweigh the risks, especially if you have a heart condition or a history of long QT.
- Expect possible periodic ECGs and blood tests to check potassium and magnesium.
- Ask before starting any new medicine, since some can also affect QT or lower these minerals.
Tell your pharmacist or doctor about 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) A study examined male patients on androgen deprivation therapy (ADT) using individual case safety reports from VigiBase, the international pharmacovigilance database, and found 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% of cases fatal), along with 99 cases of sudden death linked to ADT. The majority of aLQTS/TdP cases (62%) and sudden death cases (88%) associated with ADT arose without exposure to other agents known to raise TdP risk; nonetheless, exposure to 1 drug and to 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. The agents classified as ADTs included abiraterone, gonadotropin-releasing hormone agonists and antagonists, nonsteroidal androgen receptor inhibitors indicated for prostate cancer, and 5-alpha-reductase inhibitors indicated 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 mainly receiving ADT for prostate cancer, with some being treated for prostatism and androgenic alopecia. Most patients received ADT as monotherapy (83%), while 17% received ADT combination therapy 3.
Common questions
Can I take Relugolix and Efavirenz together?
Efavirenz and relugolix can each prolong the QT interval, and the effect may add up, so your care team may avoid the combination or monitor your ECG and electrolytes if you take both. Do not stop either drug on your own; talk with your doctor or pharmacist. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Efavirenz 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 Relugolix and Efavirenz interaction managed?
This combination can add to QT prolongation, so your care team manages it by keeping a close watch rather than leaving it to chance. Keep taking both as prescribed unless your doctor tells you otherwise. Your team may weigh whether the benefits of therapy outweigh the risks, especially if you have a heart condition or a history of long QT. Expect possible periodic ECGs and blood tests to check pot… 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 Relugolix or Efavirenz 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 Efavirenz
Keep reading about Relugolix
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