Relugolix and Tolterodine: 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
Tolterodine
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 of your medicines can gently affect your heart's electrical rhythm in the same way. Tolterodine (Detrol), used for an overactive bladder, and relugolix (Orgovyx), used in prostate cancer treatment, can each stretch out a part of the heartbeat called the QT interval. Taking them together may add up and slightly raise the chance of an irregular heartbeat.
The good news is that this concern is mostly theoretical, and your care team can manage it well. They may check an ECG (heart tracing) and your blood minerals from time to time. Please keep taking both as prescribed and ask your pharmacist or doctor if you have questions.
Effect: Additive QT interval prolongation with combined tolterodine and relugolix.
Mechanism: Pharmacodynamic (additive), not a metabolic interaction. Tolterodine has QT-prolonging potential, and androgen deprivation from GnRH antagonists like relugolix can also prolong QT. Neither drug is a prodrug relevant here.
- Direction: Additive risk of QTc prolongation / torsades.
- Onset: Unspecified.
- Evidence: Theoretical.
- Management: Avoid combination when feasible. If required, correct and avoid hypokalemia/hypomagnesemia, and perform periodic ECG and electrolyte monitoring. Weigh benefit/risk in congenital long QT, CHF, or frequent electrolyte disturbances.
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. GnRH agonists and antagonists can lengthen the QT interval through the androgen deprivation they produce. In patients who have congenital long QT syndrome, congestive heart failure, or recurrent electrolyte disturbances, as well as in those receiving other 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 alongside QT prolonging agents. Should combined use be necessary, refrain from using medications that produce electrolyte disturbances (that is, hypokalemia or hypomagnesemia) 2, rectify any electrolyte disturbances, and think about intermittent 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 combination safely. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your team may check an ECG (heart tracing) and your blood electrolytes (potassium and magnesium) from time to time.
- Low potassium or magnesium can add to the risk, so those are corrected and monitored.
- Your prescriber will weigh the benefits against the risks, especially if you have a heart rhythm condition, heart failure, or frequent electrolyte problems.
Tell your pharmacist or doctor about any fainting, dizziness, or a racing or irregular heartbeat.
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 the international pharmacovigilance database VigiBase, identifying 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% fatal cases), 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 drugs recognized to raise TdP risk; nevertheless, use of 1 drug and 2 or more drugs carrying conditional, possible, or known TdP risk was reported in some 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 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. 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 primarily 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 Tolterodine together?
Tolterodine and relugolix can each prolong the QT interval, so together they may add up and slightly raise the risk of an irregular heartbeat. Keep taking both as prescribed and let your care team monitor your ECG and electrolytes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Tolterodine 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 Tolterodine interaction managed?
Your care team can manage this combination safely. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your team may check an ECG (heart tracing) and your blood electrolytes (potassium and magnesium) from time to time. Low potassium or magnesium can add to the risk, so those are corrected and monitored. Your prescriber will weigh the benefits against the ri… 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 Tolterodine 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 Tolterodine
Keep reading about Relugolix
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