Relugolix and Lofexidine: 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
Lofexidine
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.
These two medicines can each affect your heart's rhythm in the same way. Lofexidine (used to ease opioid withdrawal) and relugolix (Orgovyx, used to lower testosterone in prostate cancer) can both stretch out a part of your heartbeat called the QT interval. When you take them together, that effect can add up, and in rare cases a longer QT can lead to a dangerous heart rhythm.
This is a theoretical concern, meaning it is based on how the drugs work rather than lots of reports. The good news is your care team can manage it, by checking your heart tracing (ECG), watching your blood minerals, and tailoring your plan. Please don't stop either drug on your own; just talk with your pharmacist or doctor.
Additive QT prolongation. Both agents independently prolong the QT interval (relugolix via androgen deprivation; lofexidine has documented QT effects), so concurrent use produces additive pharmacodynamic risk. Neither is a prodrug and this is not a metabolic interaction.
- Direction: increased risk of QTc prolongation / torsades de pointes.
- Evidence: theoretical; magnitude not quantified. Onset unspecified.
- Higher-risk patients: congenital long QT, CHF, electrolyte abnormalities, other QT-prolonging drugs.
- Management: avoid combination when possible; weigh ADT benefit vs risk. If required, avoid agents causing hypokalemia/hypomagnesemia, correct electrolytes, and perform periodic ECG and electrolyte monitoring.
What happens
Increased risk of QT interval prolongation
Interaction Deep Dive
When relugolix is given alongside 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 for prolonging the QT interval, weigh whether the advantages of androgen deprivation therapy such as relugolix justify the possible risks 1. Where feasible, do not use relugolix together with agents that prolong QT. Should combined use be necessary, refrain from using medications 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
Both drugs can lengthen the QT interval, so your care team will decide whether using them together is worth it and will keep a close eye on your heart if you do.
- Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise.
- Your team may check periodic ECGs and blood electrolytes (like potassium and magnesium) and correct any that are low.
- They may avoid other medicines that lower those minerals or add to QT risk.
- Tell your care team if you have a heart rhythm problem, heart failure, or a family history of long QT syndrome, and report fainting, dizziness, or palpitations right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A study assessing male patients on androgen deprivation therapy (ADT) using individual case safety reports from the international pharmacovigilance database VigiBase 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%) associated with ADT arose without exposure to other agents known to raise TdP risk; nevertheless, exposure to 1 drug and 2 or more drugs at conditional, possible, or known TdP risk was reported in a portion of aLQTS/TdP (23% or 43%) and sudden death (18% and 22%) events. 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 received ADT monotherapy (83%); 17% were on ADT combination therapy 3.
Common questions
Can I take Relugolix and Lofexidine together?
Lofexidine and relugolix can each prolong the QT interval, and using them together adds to that risk. Take both as prescribed and let your care team know so they can monitor your ECG and electrolytes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Lofexidine 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 Lofexidine interaction managed?
Both drugs can lengthen the QT interval, so your care team will decide whether using them together is worth it and will keep a close eye on your heart if you do. Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise. Your team may check periodic ECGs and blood electrolytes (like potassium and magnesium) and correct any that are low. They may avoid other medicines that… 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 Lofexidine 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 Lofexidine
Keep reading about Relugolix
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist