Relugolix and Posaconazole: 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
Posaconazole
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.
You've been prescribed two medicines that can each affect your heart's rhythm. Posaconazole (Noxafil), an antifungal, and relugolix (Orgovyx), used in prostate cancer treatment, can both stretch out a part of your heartbeat called the QT interval. When taken together, that effect can add up, which in rare cases can lead to an irregular heartbeat.
This is a theoretical concern based on how these drugs work, not something proven to happen to everyone. The good news is your care team can manage it easily, often with a simple heart tracing (ECG) and blood tests to check your minerals like potassium and magnesium. Please keep taking both as prescribed and talk with your pharmacist or doctor about this.
Additive QT prolongation. Both agents can independently prolong the QT interval, posaconazole via known hERG-related effects and relugolix via androgen deprivation. Coadministration produces additive PD risk of QTc prolongation and, rarely, torsades de pointes. Neither is a prodrug here; this is a pharmacodynamic, not PK, interaction.
- Direction: increased QT prolongation risk (additive)
- Evidence: theoretical; severity: major; onset: unspecified
- Management: avoid combination when feasible; weigh ADT benefit vs risk, especially with congenital long QT, CHF, or electrolyte disturbances. If used together, correct and maintain normal K+/Mg2+, avoid other electrolyte-depleting agents, and consider 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 can itself lengthen the QT interval. For patients who have congenital long QT syndrome, congestive heart failure, or recurrent electrolyte abnormalities, as well as those receiving drugs recognized to prolong the QT interval, weigh whether the benefits of androgen deprivation therapy such as relugolix outweigh the potential risks 1. Where feasible, do not use relugolix alongside QT prolonging agents. Should coadministration be necessary, steer clear of drugs that produce electrolyte abnormalities (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
Your care team has ways to keep this safe. Depending on your situation, they may:
- Decide whether both drugs are truly needed together, or whether an alternative is possible
- Check your heart rhythm with periodic ECGs
- Monitor and correct blood minerals like potassium and magnesium, and avoid other things that lower them
What you should do: Keep taking both medicines exactly as prescribed, and don't stop either on your own. Tell your pharmacist or prescriber about any fainting, dizziness, or a fluttering or pounding heartbeat, and mention any history of heart rhythm problems.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A study assessing male patients on androgen deprivation therapy (ADT) using individual case safety reports from VigiBase, the international pharmacovigilance database, identified 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% fatal cases), 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 recognized as increasing TdP risk; nevertheless, exposure to 1 drug and to 2 or more drugs carrying conditional, possible, or known TdP risk was reported in a portion of aLQTS/TdP (23% or 43%) and sudden death (18% and 22%) events. The agents regarded 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 patients had a median age of about 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 chiefly for prostate cancer, with some treated for prostatism and androgenic alopecia. Most patients were on ADT monotherapy (83%); 17% were receiving ADT combination therapy 3.
Common questions
Can I take Relugolix and Posaconazole together?
Taking posaconazole and relugolix together can add up their effects on your heart's rhythm (QT interval); keep taking both as prescribed and let your care team monitor your ECG and electrolytes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Posaconazole 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 Posaconazole interaction managed?
Your care team has ways to keep this safe. Depending on your situation, they may: Decide whether both drugs are truly needed together, or whether an alternative is possible Check your heart rhythm with periodic ECGs Monitor and correct blood minerals like potassium and magnesium, and avoid other things that lower them What you should do: Keep taking both medicines exactly as prescribed, and don't… 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 Posaconazole 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 Posaconazole
Keep reading about Relugolix
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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