Relugolix and Quetiapine: 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
Quetiapine
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.
Both of these medicines can affect your heart's rhythm in a similar way. Quetiapine (Seroquel) can slightly stretch out part of your heartbeat, called the QT interval, and relugolix (Orgovyx), which lowers testosterone as part of prostate cancer treatment, can do the same thing. Taken together, those effects can add up, which in rare cases could lead to an irregular heartbeat.
This concern is based on how the drugs work rather than lots of real-world reports, so try not to worry. Your care team can manage it by keeping an eye on your heart and your blood minerals like potassium and magnesium. Please don't stop either medicine on your own, just talk with your doctor or pharmacist.
Effect: Additive QT interval prolongation. Both agents independently prolong the QT interval (quetiapine via a PD effect on cardiac repolarization; relugolix via androgen deprivation), so the interaction is pharmacodynamic and additive, not metabolic. Neither is a prodrug here.
- Severity/evidence: Major, but theoretical.
- Risk factors: Congenital long QT, CHF, bradycardia, hypokalemia/hypomagnesemia, other QT-prolonging drugs.
- Management: Avoid combination when possible. If required, correct and maintain electrolytes, avoid additional QT-prolonging or electrolyte-depleting agents, and consider periodic ECG and electrolyte monitoring. Weigh benefits of ADT against arrhythmia risk.
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. In patients who have congenital long QT syndrome, congestive heart failure, or recurrent electrolyte disturbances, as well as those receiving drugs recognized to prolong the QT interval, weigh whether the advantages of androgen deprivation therapy such as relugolix outweigh the possible hazards 1. Where feasible, do not use relugolix concurrently with QT prolonging agents. When such combined use cannot be avoided, refrain from using 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 can manage this combination safely. Here is what they typically do:
- Weigh the benefit: confirm that the cancer treatment (relugolix) is worth continuing given your heart history.
- Watch your heart: they may check periodic ECGs (heart tracings).
- Check your minerals: keeping potassium and magnesium in a normal range lowers the risk, so they may test and correct these.
What you can do: keep taking both exactly as prescribed unless told otherwise, and tell your pharmacist or prescriber if you feel faint, dizzy, or notice a racing or pounding heartbeat. Also mention any other medicines you take.
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 the international pharmacovigilance database VigiBase 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 drugs recognized to elevate TdP risk; nevertheless, exposure to 1 drug and to 2 or more drugs carrying conditional, possible, or known TdP risk was reported in some aLQTS/TdP events (23% or 43%) and sudden death events (18% and 22%). The drugs 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 evaluated, 7 demonstrated 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 roughly 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 receiving ADT chiefly to treat prostate cancer, with some receiving therapy 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 Quetiapine together?
Quetiapine and relugolix can each prolong the QT interval, and together the effect may add up, so your care team may monitor your heart rhythm and blood minerals. 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 Relugolix and Quetiapine 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 Quetiapine interaction managed?
Your care team can manage this combination safely. Here is what they typically do: Weigh the benefit: confirm that the cancer treatment (relugolix) is worth continuing given your heart history. Watch your heart: they may check periodic ECGs (heart tracings). Check your minerals: keeping potassium and magnesium in a normal range lowers the risk, so they may test and correct these. What you can do:… 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 Quetiapine 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 Quetiapine
Keep reading about Relugolix
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