Granisetron 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
Granisetron
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.
These two medicines can each have a small effect on your heart's electrical rhythm, something called the QT interval. Granisetron (used to prevent nausea) and relugolix (used to lower testosterone in prostate cancer) can each nudge that timing a little, and taken together the effects can add up. In rare cases a longer QT can lead to an irregular heartbeat.
Please don't stop either one on your own. This is mostly a caution rather than something that happens to everyone. Your care team can keep you safe by checking your heart tracing (ECG) and your blood minerals like potassium and magnesium. Let them know if you feel dizzy, faint, or notice a pounding or fluttering heartbeat.
Effect: Additive QT interval prolongation from concurrent granisetron and relugolix. Both are pharmacodynamic (not prodrug) contributors; androgen deprivation from relugolix can itself prolong QT, and granisetron (a 5-HT3 antagonist) carries recognized QT risk.
- Direction: Additive PD effect, increased torsadogenic risk.
- Onset: Unspecified.
- Evidence: Theoretical.
- Magnitude: Not quantified.
Management: Avoid combination when possible. Higher caution with congenital long QT, CHF, or electrolyte disturbance. If used together, avoid agents causing hypokalemia/hypomagnesemia, correct electrolytes, 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. 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, clinicians should weigh whether the benefits of androgen deprivation therapy such as relugolix are greater than the possible risks 1. Where feasible, do not use relugolix alongside QT prolonging agents. Should coadministration be necessary, refrain from using medications that produce electrolyte abnormalities (that is, hypokalemia or hypomagnesemia) 2, correct any electrolyte abnormalities, and consider periodic ECG and electrolyte monitoring 1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Both drugs can add to a mild effect on your heart rhythm, so your care team will weigh the benefits against the risks and watch you if you take them together.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your team may check periodic ECGs and blood levels of potassium and magnesium, and correct any that are low.
- Tell your care team if you have a history of long QT syndrome, heart failure, or frequent electrolyte problems.
- Report fainting, dizziness, or an irregular or pounding heartbeat promptly.
Ask your pharmacist or doctor whether this combination is right for you.
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 found 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% 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 raise TdP risk; nevertheless, use of 1 drug and 2 or more drugs carrying conditional, possible, or known TdP risk was documented in a portion of aLQTS/TdP events (23% or 43%) and sudden death events (18% and 22%). 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 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 receiving it for prostatism and androgenic alopecia. Most patients were on ADT monotherapy (83%); 17% were on ADT combination therapy 3.
Common questions
Can I take Granisetron and Relugolix together?
Granisetron and relugolix can each affect heart rhythm (QT), and together the risk adds up, so your care team may monitor your ECG and electrolytes. Keep taking both as prescribed and report any fainting or irregular heartbeat. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Granisetron 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 Granisetron and Relugolix interaction managed?
Both drugs can add to a mild effect on your heart rhythm, so your care team will weigh the benefits against the risks and watch you if you take them together. Keep taking both as prescribed unless your prescriber tells you otherwise. Your team may check periodic ECGs and blood levels of potassium and magnesium, and correct any that are low. Tell your care team if you have a history of long QT synd… 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 Granisetron 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 Granisetron
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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