Tacrolimus and Relugolix: 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
Tacrolimus
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 tacrolimus and relugolix can affect the electrical timing of your heartbeat, something doctors call the QT interval. When two medicines that each do this are taken together, the effect can add up and, in rare cases, lead to an abnormal heart rhythm.
This concern is based on theory and how these drugs work, not on lots of reported cases, so try not to worry. Your care team knows how to watch for this. They may check your heart rhythm with an EKG and keep an eye on blood minerals like potassium and magnesium. Keep taking both medicines as prescribed, and ask your pharmacist or doctor if you have questions.
Effect: Additive QT interval prolongation (pharmacodynamic interaction). Both agents are independently associated with QT prolongation; relugolix via androgen deprivation, tacrolimus as a known QT-prolonging agent.
Direction: Increased torsadogenic risk. Neither drug is a prodrug; this is purely PD, not PK.
Evidence: Theoretical. Onset: unspecified.
Management:
- Avoid concomitant use when feasible; weigh ADT benefit against risk, especially with congenital long QT, CHF, or recurrent electrolyte disturbance.
- If combined, correct and avoid hypokalemia/hypomagnesemia.
- 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 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 risks 1. Where feasible, do not combine relugolix 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 electrolytes 1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
Your care team can manage this safely. Typical steps include:
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your team may order periodic EKGs to check your heart rhythm.
- They may check potassium and magnesium levels and correct them if low, since low levels raise the risk.
- In some cases, your doctor may weigh whether the benefit of relugolix outweighs the risk, particularly if you have a heart rhythm condition or heart failure.
Tell your pharmacist or prescriber if you feel faint, dizzy, or notice a fluttering 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 on 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 cases 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 medications known to elevate TdP risk; nevertheless, exposure to 1 drug and to 2 or more drugs carrying conditional, possible, or known TdP risk was documented in a portion of aLQTS/TdP events (23% or 43%) and sudden death events (18% and 22%). The drugs regarded 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 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 mainly receiving ADT for prostate cancer treatment, with some being 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 Tacrolimus and Relugolix together?
Taking tacrolimus and relugolix together can add up to prolong the QT interval, so your care team may monitor your EKG and electrolytes; keep taking both as prescribed and report any dizziness or irregular heartbeat. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tacrolimus and Relugolix 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 Tacrolimus and Relugolix interaction managed?
Your care team can manage this safely. Typical steps include: Keep taking both as prescribed unless your prescriber tells you otherwise. Your team may order periodic EKGs to check your heart rhythm. They may check potassium and magnesium levels and correct them if low, since low levels raise the risk. In some cases, your doctor may weigh whether the benefit of relugolix outweighs the risk, particu… 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 Tacrolimus or Relugolix 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 Tacrolimus
Keep reading about Relugolix
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