Relugolix and Selpercatinib: 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
Selpercatinib
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 selpercatinib (Retevmo) and relugolix (Orgovyx) can affect your heart's electrical rhythm. Each one can stretch out a 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 an irregular heartbeat.
The good news is this concern is based on how the drugs work, not on lots of real-world problems. Your care team knows about it and can keep you safe by checking your heart tracing (ECG) and your blood minerals like potassium and magnesium. Keep taking both as prescribed, and talk with your pharmacist or doctor if you feel dizzy, faint, or notice a fluttering heartbeat.
Effect: Additive QT interval prolongation when selpercatinib is combined with relugolix. Both agents (plus the androgen deprivation caused by relugolix) independently prolong the QT interval; the risk is pharmacodynamic, not a metabolic (PK) interaction.
- Direction: Additive increase in QT prolongation risk / torsades potential.
- Severity: Major. Onset: Unspecified. Evidence: Theoretical.
- Higher-risk patients: Congenital long QT, CHF, electrolyte abnormalities.
- Management: Avoid combination when possible. If required, correct and maintain normal K+ and Mg2+, avoid agents causing hypokalemia/hypomagnesemia, and 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 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, refrain from using drugs that produce electrolyte disturbances (that is, hypokalemia or hypomagnesemia) 2, correct any electrolyte disturbances, 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 by watching your heart and blood levels rather than leaving it to chance.
- Keep taking both exactly as prescribed unless your doctor tells you otherwise.
- Your team may order periodic ECGs and blood tests for potassium and magnesium, and correct any low levels.
- They may review whether the benefit of therapy outweighs the risk, especially if you have a known long QT condition, heart failure, or frequent electrolyte problems.
- Tell your pharmacist or doctor about fainting, dizziness, or palpitations, and mention other medicines you take, since some also affect QT.
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 detected 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% of cases fatal), plus 99 cases of sudden death linked to ADT. The majority of aLQTS/TdP cases (62%) and sudden death cases (88%) related to ADT arose without concurrent use of other agents known to raise TdP risk; nevertheless, use of 1 drug and 2 or more drugs with conditional, possible, or known TdP risk was documented in a portion of the 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 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 median patient age was 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 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 on ADT combination therapy 3.
Common questions
Can I take Relugolix and Selpercatinib together?
Taking selpercatinib and relugolix together can add up their effects on the heart's QT interval; your care team can manage this with ECG and electrolyte monitoring, so 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 Selpercatinib 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 Selpercatinib interaction managed?
Your care team can manage this by watching your heart and blood levels rather than leaving it to chance. Keep taking both exactly as prescribed unless your doctor tells you otherwise. Your team may order periodic ECGs and blood tests for potassium and magnesium, and correct any low levels. They may review whether the benefit of therapy outweighs the risk, especially if you have a known long QT con… 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 Selpercatinib 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 Selpercatinib
Keep reading about Relugolix
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