Relugolix and Hydroxyzine: 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
Hydroxyzine
No brand names on recordRelugolix
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 hydroxyzine (an antihistamine often used for anxiety, itching, or sleep) and relugolix (Orgovyx, used to lower testosterone in prostate cancer). Both of these drugs can affect the timing of your heartbeat, something called the QT interval. When taken together, that effect can add up and, in rare cases, lead to an irregular heartbeat.
The good news is that this concern is mostly theoretical, and your care team knows how to keep it in check. They may check an ECG (heart tracing) and your blood minerals like potassium and magnesium 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 from concurrent hydroxyzine and relugolix.
- Mechanism: Both agents independently prolong the QT interval; androgen deprivation via GnRH antagonism (relugolix) can prolong QT, and hydroxyzine has intrinsic QT-prolonging potential. Effects are additive (pharmacodynamic, not PK). Neither is a prodrug relevant here.
- Direction: Increased risk of QTc prolongation / torsades de pointes.
- Evidence: Theoretical; severity rated major. Onset unspecified.
- Management: Avoid combination when feasible. If required, correct and maintain normal K+ and Mg2+, avoid other electrolyte-depleting drugs, and consider periodic ECG and electrolyte monitoring. Heightened caution 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. The androgen deprivation produced by GnRH agonists or antagonists can itself lengthen the QT interval. In patients with congenital long QT syndrome, congestive heart failure, or recurrent electrolyte disturbances, as well as in those receiving agents recognized to prolong the QT interval, weigh whether the benefits of androgen deprivation therapy such as relugolix outweigh the possible risks 1. Where feasible, do not use relugolix alongside QT prolonging agents. Should coadministration be necessary, refrain from using drugs that produce electrolyte disturbances (that is, hypokalemia or hypomagnesemia) 2, correct any electrolyte disturbances, 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 by watching your heart rhythm and blood minerals.
- Keep taking both exactly as prescribed unless your prescriber tells you otherwise.
- Where possible, this combination is avoided; if you need both, your team may check ECGs and electrolytes (potassium and magnesium) from time to time and correct any low levels.
- Tell your team if you have a history of long QT syndrome, heart failure, or frequent electrolyte problems.
- Report symptoms like fainting, dizziness, or a fluttering or racing heartbeat right away.
- Mention all other medicines, since some also affect the QT interval or lower electrolytes.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A study of male patients on androgen deprivation therapy (ADT) that used individual case safety reports from VigiBase, the international pharmacovigilance database, identified 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% fatal cases), together with 99 cases of sudden death associated with ADT. The majority of aLQTS/TdP cases (62%) and sudden death cases (88%) associated with ADT arose without exposure to other agents known to raise TdP risk; nevertheless, exposure to 1 drug and to 2 or more drugs carrying conditional, possible, or known TdP risk was reported in a portion of aLQTS/TdP (23% or 43%) and sudden death (18% and 22%) events. 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 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 chiefly for prostate cancer, 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 Hydroxyzine together?
Both hydroxyzine and relugolix can prolong the QT interval, so together they may add to the risk of an irregular heartbeat. This combination is best avoided when possible, but if you need both, your care team can manage it with ECG and electrolyte monitoring. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Hydroxyzine 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 Hydroxyzine interaction managed?
Your care team can manage this by watching your heart rhythm and blood minerals. Keep taking both exactly as prescribed unless your prescriber tells you otherwise. Where possible, this combination is avoided; if you need both, your team may check ECGs and electrolytes (potassium and magnesium) from time to time and correct any low levels. Tell your team if you have a history of long QT syndrome, h… 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Relugolix or Hydroxyzine 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 Hydroxyzine
Keep reading about Relugolix
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