Relugolix and Methotrimeprazine: 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
Methotrimeprazine
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 two medicines that can each affect your heart's rhythm. Methotrimeprazine (a phenothiazine used for pain, agitation, or nausea) and relugolix (Orgovyx, used to lower testosterone in prostate cancer) can both stretch out part of the heartbeat called the QT interval. When you take them together, that effect can add up, which in rare cases can lead to a dangerous irregular heartbeat.
The good news is this is a known, manageable concern. Your care team may check an ECG (heart tracing) and your blood minerals like potassium and magnesium. Please don't stop either medicine on your own. Talk with your pharmacist or doctor about the best plan for you.
Effect: Additive QT interval prolongation, with increased torsades de pointes risk.
Mechanism: Both agents independently prolong the QT interval. Methotrimeprazine (a phenothiazine) has intrinsic QT effects; androgen deprivation from relugolix (a GnRH antagonist) can also prolong QT. This is a pharmacodynamic (additive), not pharmacokinetic, interaction. Neither drug's activation depends on the other.
Evidence: Theoretical. Severity: Major. Onset: Unspecified.
- Avoid concomitant use when possible.
- Weigh ADT benefit vs risk in congenital long QT, CHF, or recurrent electrolyte disturbance.
- If combined: correct and avoid hypokalemia/hypomagnesemia; perform 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 those receiving drugs recognized to prolong the QT interval, weigh whether the advantages of androgen deprivation therapy such as relugolix are greater than the possible hazards 1. Where feasible, do not use relugolix at the same time as QT prolonging agents. Should combined use be necessary, refrain from using drugs that produce electrolyte disturbances (that is, hypokalemia or hypomagnesemia) 2, correct any electrolyte abnormalities, and think about periodically monitoring ECGs and electrolytes 1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Both drugs can affect your heart rhythm, so your care team manages this carefully rather than leaving it to chance.
- Keep taking both exactly as prescribed unless your doctor tells you otherwise.
- Your team may check ECGs and blood electrolytes (potassium and magnesium) from time to time.
- They will work to keep those minerals in a healthy range, since low levels raise the risk.
- Where possible, your team may consider whether an alternative to one drug is a better fit.
Tell your pharmacist or doctor if you feel faint, dizzy, have a racing or irregular heartbeat, or take other medicines that affect the heart. Mention any personal or family 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 assessed male patients undergoing androgen deprivation therapy (ADT) using individual case safety reports from VigiBase, the international pharmacovigilance database, and 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%) associated with ADT arose without concurrent use of other agents known to raise TdP risk; nonetheless, use of 1 drug and of 2 or more drugs carrying conditional, possible, or known TdP risk was documented in some aLQTS/TdP (23% or 43%) and sudden death (18% and 22%) events. The agents classified as ADTs comprised 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 primarily receiving ADT for prostate cancer, with some treated for prostatism and androgenic alopecia. The majority of patients were on ADT monotherapy (83%); 17% were receiving ADT combination therapy 3.
Common questions
Can I take Relugolix and Methotrimeprazine together?
Taking methotrimeprazine and relugolix together can add up their effects on heart rhythm (QT prolongation), so your care team may monitor ECGs and electrolytes; keep taking both as prescribed and report any dizziness, fainting, or palpitations. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Methotrimeprazine 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 Methotrimeprazine interaction managed?
Both drugs can affect your heart rhythm, so your care team manages this carefully rather than leaving it to chance. Keep taking both exactly as prescribed unless your doctor tells you otherwise. Your team may check ECGs and blood electrolytes (potassium and magnesium) from time to time. They will work to keep those minerals in a healthy range, since low levels raise the risk. Where possible, your… 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 Methotrimeprazine 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 Methotrimeprazine
Keep reading about Relugolix
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