Relugolix and Fingolimod: 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
Fingolimod
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 fingolimod (Gilenya) and relugolix (Orgovyx) can affect the heart's electrical timing, something doctors call the QT interval. When you take them together, those effects can add up and, in rare cases, lead to an irregular heartbeat.
The good news is this concern is mostly theoretical, and your care team can manage it well. They may check an ECG (a heart tracing) and your blood levels of minerals like potassium and magnesium now and then. Please don't stop either medicine on your own. Just let your pharmacist or doctor know you take both, and tell them if you ever feel dizzy, faint, or notice a fluttering heartbeat.
Additive QT prolongation. Both agents are independently associated with QTc prolongation (fingolimod also causes bradycardia/AV effects on initiation; relugolix prolongs QT via androgen deprivation). Combined use is a pharmacodynamic, additive interaction, not a metabolic one. Neither is a relevant prodrug here.
- Direction/effect: increased risk of QT prolongation and torsades.
- Evidence: theoretical; severity: major; onset unspecified.
- Management: avoid combination when possible; weigh ADT benefit vs risk in congenital long QT, CHF, or frequent electrolyte disturbance. If used together, correct/maintain K+ and Mg2+, avoid other electrolyte-depleting or QT-prolonging drugs, and obtain periodic ECGs and electrolyte panels.
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 are greater than the possible risks 1. Whenever feasible, do not use relugolix at the same time as QT prolonging agents. When such coadministration cannot be avoided, refrain from using medications that produce electrolyte disturbances (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 safely, usually by keeping an eye on things rather than making dramatic changes.
- Keep taking both exactly as prescribed unless your doctor tells you otherwise.
- Your team may order periodic ECGs and check electrolytes (potassium and magnesium), correcting any that run low.
- They may review whether other medicines you take also affect the QT interval or lower electrolytes.
- Tell your pharmacist or doctor about all your medicines, and report fainting, palpitations, or dizziness promptly.
In some cases they may decide an alternative is safer, but that is their call to make with you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A study looked at male patients on androgen deprivation therapy (ADT) using individual case safety reports from the international pharmacovigilance database VigiBase, identifying 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; nevertheless, use of 1 drug and 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 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 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 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 mainly receiving ADT for prostate cancer, with some being treated for prostatism and androgenic alopecia. Most patients were on ADT monotherapy (83%); 17% were on ADT combination therapy 3.
Common questions
Can I take Relugolix and Fingolimod together?
Taking fingolimod and relugolix together can add to the risk of QT prolongation, so your care team may monitor your ECG and electrolytes. 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 Fingolimod 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 Fingolimod interaction managed?
Your care team can manage this safely, usually by keeping an eye on things rather than making dramatic changes. Keep taking both exactly as prescribed unless your doctor tells you otherwise. Your team may order periodic ECGs and check electrolytes (potassium and magnesium), correcting any that run low. They may review whether other medicines you take also affect the QT interval or lower electrolyt… 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 Fingolimod 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 Fingolimod
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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