Relugolix and Ivosidenib: 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
Ivosidenib
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, ivosidenib (Tibsovo) and relugolix (Orgovyx), can affect your heart's electrical rhythm in a similar way. Doctors call this QT prolongation. When two medicines that both do this are taken together, the effect can add up and, in rare cases, lead to an irregular heartbeat.
Please don't worry or change anything on your own. This is something your care team knows how to manage. They may check your heart with an EKG now and then, keep an eye on your blood minerals (like potassium and magnesium), and make sure everything stays balanced. If you ever feel dizzy, faint, or notice a fluttering heartbeat, tell your doctor right away.
Effect: Additive QT interval prolongation with concurrent ivosidenib and relugolix.
Mechanism: Both agents independently prolong the QT interval (ivosidenib directly; relugolix via androgen deprivation). Effect is pharmacodynamic and additive, not a metabolic (PK) interaction. Neither is a prodrug here.
- Severity: Major; evidence: theoretical; onset: unspecified.
- Higher risk with congenital long QT syndrome, CHF, or electrolyte abnormalities.
- Management: Avoid combination when possible. If required, correct and maintain normal K+ and Mg2+, avoid other QT-prolonging or electrolyte-depleting agents, and perform periodic ECG and electrolyte monitoring.
What happens
Increased risk of QT interval prolongation
Interaction Deep Dive
When relugolix is given together with drugs that prolong the QT interval, the effects on the QT interval are additive. The androgen deprivation produced by GnRH agonists or 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 in those receiving medications known 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 concurrently with QT prolonging agents. When coadministration cannot be avoided, refrain from using drugs 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
Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. Here is how a team usually handles this combination:
- Weighing benefits and risks, especially if you have a heart rhythm condition, heart failure, or trouble keeping your minerals balanced.
- Checking EKGs periodically to watch your heart rhythm.
- Monitoring blood electrolytes (potassium and magnesium) and correcting any that are low.
- Reviewing your other medicines to avoid additional QT-prolonging drugs when possible.
Ask your pharmacist or prescriber before starting any new medication, and report dizziness, fainting, or palpitations promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In an analysis of male patients receiving androgen deprivation therapy (ADT) using individual case safety reports from VigiBase, the international pharmacovigilance database, investigators 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 exposure to other agents known to elevate TdP risk; nonetheless, use of 1 drug and 2 or more drugs carrying conditional, possible, or known TdP risk was reported in a portion of 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. 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 receiving ADT mainly for prostate cancer treatment, with some treated for prostatism and androgenic alopecia. Most patients were on ADT monotherapy (83%); 17% were receiving ADT combination therapy 3.
Common questions
Can I take Relugolix and Ivosidenib together?
Taking ivosidenib and relugolix together can add to the risk of QT prolongation, so your care team may avoid the combination when possible or monitor your EKG and electrolytes closely. Keep both medicines as prescribed and report any dizziness, fainting, or irregular heartbeat. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Ivosidenib 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 Ivosidenib interaction managed?
Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. Here is how a team usually handles this combination: Weighing benefits and risks, especially if you have a heart rhythm condition, heart failure, or trouble keeping your minerals balanced. Checking EKGs periodically to watch your heart rhythm. Monitoring blood electrolytes (potassium and magnesium) and corr… 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 Ivosidenib 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 Ivosidenib
Keep reading about Relugolix
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