Relugolix and Inotuzumab Ozogamicin: 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
Inotuzumab Ozogamicin
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.
You've been prescribed two medicines, relugolix (Orgovyx) and inotuzumab ozogamicin (Besponsa). Both can affect the heart's electrical rhythm in a similar way. Doctors call this QT prolongation, which means the heart takes a little longer to reset between beats. When two medicines that both do this are taken together, their effects can add up, which slightly raises the chance of an irregular heartbeat.
The good news is that this is a known, manageable concern. Your care team can keep an eye on things with heart tracings (ECGs) and blood tests, and they'll make sure your medicines are the right fit for you. Keep taking both as prescribed, and bring up any dizziness, fainting, or palpitations with your doctor or pharmacist.
Effect: Additive risk of QT interval prolongation with concurrent relugolix and inotuzumab ozogamicin. Both agents are independently associated with QTc prolongation (relugolix via androgen deprivation; inotuzumab per labeling), so the interaction is pharmacodynamic and additive, not a metabolic (PK) interaction. Neither is a prodrug relevant here.
- Severity/evidence: Major, but theoretical/additive.
- Onset: Unspecified.
- Risk factors: Congenital long QT, CHF, electrolyte abnormalities (hypokalemia, hypomagnesemia).
- Management: Avoid concomitant use when possible. If required, correct and maintain electrolytes, avoid other QT-prolonging or electrolyte-depleting agents, and perform periodic ECG and electrolyte monitoring. Weigh benefits of ADT against arrhythmic risk.
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 or antagonists can itself lengthen the QT interval. In patients who have congenital long QT syndrome, congestive heart failure, or recurrent electrolyte abnormalities, 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 at the same time as 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 of these drugs can lengthen the QT interval, so a care team manages them together carefully rather than leaving anything to chance. Keep taking both exactly as prescribed unless your prescriber tells you otherwise.
- Your team may check ECGs (heart tracings) and blood electrolytes (like potassium and magnesium) from time to time.
- They will correct any low potassium or magnesium and try to avoid other medicines that lower these levels or prolong QT.
- Where possible, they may consider alternatives or weigh the benefits of therapy against the risks.
Tell your pharmacist or doctor promptly if you feel faint, dizzy, or notice a pounding or irregular heartbeat, and share your full medication list.
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 drawn from VigiBase, the international pharmacovigilance database. It identified 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%) related to ADT arose without concurrent use of other agents known to elevate TdP risk; nonetheless, use of 1 drug and of 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 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' median 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, with some 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 Inotuzumab Ozogamicin together?
Relugolix and inotuzumab ozogamicin can both prolong the QT interval, and the effect can add up, so your care team may monitor ECGs and electrolytes and keep other QT-affecting drugs to a minimum. Report any fainting, dizziness, or irregular heartbeat. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Inotuzumab Ozogamicin 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 Inotuzumab Ozogamicin interaction managed?
Both of these drugs can lengthen the QT interval, so a care team manages them together carefully rather than leaving anything to chance. Keep taking both exactly as prescribed unless your prescriber tells you otherwise. Your team may check ECGs (heart tracings) and blood electrolytes (like potassium and magnesium) from time to time. They will correct any low potassium or magnesium and try to avoid… 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 Inotuzumab Ozogamicin 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 Inotuzumab Ozogamicin
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