Relugolix and Degarelix: 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
Relugolix
Degarelix
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 relugolix (Orgovyx) and degarelix (Firmagon) lower testosterone to treat prostate cancer. One known side effect of this kind of therapy is a small change in the heart's electrical rhythm, called QT prolongation. When two medicines that can do this are used together, the effect may add up.
The good news is this is a theoretical concern, meaning it is based on how the drugs work rather than proven problems in people. It also would be unusual to take both of these at the same time. Your care team can manage this easily by checking your heart tracing (ECG) and your blood minerals now and then. Please don't change anything on your own, just talk with your doctor or pharmacist.
Effect: Additive QT interval prolongation. Both agents produce androgen deprivation (relugolix is a GnRH antagonist, degarelix a GnRH antagonist), and profound hypogonadism itself can prolong the QT interval.
- Direction/mechanism: Additive PD effect on cardiac repolarization; not a PK/enzyme interaction. Neither is a prodrug relevant here.
- Evidence: Theoretical; magnitude not quantified.
- Onset: Unspecified.
- Management: Avoid concomitant use where possible. If combined, weigh benefit vs risk (congenital long QT, CHF, electrolyte disturbance), avoid QT-prolonging or electrolyte-depleting drugs, correct hypokalemia/hypomagnesemia, 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 QT interval are additive. The androgen deprivation produced by GnRH agonists and antagonists can 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, weigh whether the advantages of androgen deprivation therapy such as relugolix are greater than the possible risks1. Where feasible, do not use relugolix concurrently with QT prolonging agents. Should coadministration be necessary, 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 electrolytes1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Both drugs are used for prostate cancer and both can nudge the heart's QT interval. Here is what a care team typically does:
- Prefer to avoid using two QT-prolonging drugs together when there is another option.
- Weigh the benefits of therapy against risks, especially if you have a heart rhythm condition, heart failure, or low potassium or magnesium.
- Monitor: your team may check periodic ECGs and blood electrolytes, and correct any low potassium or magnesium.
Keep taking both exactly as prescribed. Ask your pharmacist or doctor if you have a history of heart rhythm problems or take other drugs that affect the heart rhythm.
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 found 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% of cases were 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 happened without concurrent use of other agents known to raise TdP risk; nevertheless, use of 1 drug and of 2 or more drugs carrying conditional, possible, or known TdP risk was reported in a portion of the aLQTS/TdP events (23% or 43%) and sudden death events (18% and 22%). The agents classified as ADTs included abiraterone, gonadotropin-releasing hormone agonists and antagonists, nonsteroidal androgen receptor inhibitors used for prostate cancer, and 5-alpha-reductase inhibitors used 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 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 taking ADT mainly 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 Degarelix together?
Combining relugolix and degarelix can add up their effect on the heart's QT interval, so avoid using both together when possible; if both are needed, your team may monitor ECGs and keep your electrolytes in range. Do not stop either drug on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Degarelix 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 Degarelix interaction managed?
Both drugs are used for prostate cancer and both can nudge the heart's QT interval. Here is what a care team typically does: Prefer to avoid using two QT-prolonging drugs together when there is another option. Weigh the benefits of therapy against risks, especially if you have a heart rhythm condition, heart failure, or low potassium or magnesium. Monitor: your team may check periodic ECGs and blo… 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 Degarelix 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 Relugolix
Keep reading about Degarelix
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