Relugolix and Norfloxacin: 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
Norfloxacin
No brand names on record
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.
Here's what's going on. Both of these medicines can affect the timing of your heartbeat. Relugolix (Orgovyx) lowers testosterone, and that alone can slightly stretch out part of your heart's electrical cycle, called the QT interval. Norfloxacin is an antibiotic that can do the same thing. Taken together, those effects can add up, which in rare cases could lead to an irregular heartbeat.
I want you to know this concern is based on how these drugs work, not on a lot of real-world reports. Please keep taking both exactly as prescribed. Your care team can manage this easily, often by checking an ECG or your blood minerals like potassium and magnesium. Bring it up at your next visit.
Effect: Additive QT-interval prolongation with increased torsades risk. Both agents are QT-prolonging: androgen deprivation from relugolix (a GnRH antagonist) can prolong QT, and norfloxacin, a fluoroquinolone, carries intrinsic QT liability. Effect is pharmacodynamic (additive), not a metabolic/prodrug interaction.
- Direction: Additive increase in QTc.
- Evidence: Theoretical; magnitude not quantified.
- Onset: Unspecified.
Management: Avoid concomitant use when possible. Weigh benefits of ADT in patients with congenital long QT, CHF, or electrolyte abnormalities. If used together, avoid agents causing hypokalemia/hypomagnesemia, correct electrolytes, and 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 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 drugs recognized to prolong the QT interval, weigh whether the advantages of androgen deprivation therapy such as relugolix outweigh the possible risks 1. Whenever feasible, do not use relugolix alongside QT prolonging agents. Should coadministration 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
This interaction is usually manageable. Here is what a care team typically does and what you can do:
- Keep taking both as prescribed unless your prescriber tells you otherwise. Do not stop on your own.
- Your team may avoid using both together when there is a good alternative antibiotic.
- If both are needed, they may check an ECG and your blood electrolytes (potassium and magnesium) and correct any that are low.
- Tell your doctor or pharmacist if you have a history of heart rhythm problems, long QT syndrome, or heart failure.
Report fainting, dizziness, or a fluttering heartbeat right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A study assessed male patients treated with androgen deprivation therapy (ADT) using individual case safety reports from VigiBase, the international pharmacovigilance database, and found 184 cases of acquired long-QT syndrome (aLQTS) and/or torsades de pointes (TdP; 11% of which were fatal), along with 99 cases of sudden death linked to ADT. The majority of aLQTS/TdP cases (62%) and sudden death cases (88%) tied to ADT arose without concurrent use of other drugs recognized to elevate TdP risk; nevertheless, 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 (23% or 43%) and sudden death (18% and 22%) events. The drugs 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 mainly receiving ADT for prostate cancer, while some were being treated for prostatism and androgenic alopecia. Most patients were on ADT monotherapy (83%), and 17% were on ADT combination therapy 3.
Common questions
Can I take Relugolix and Norfloxacin together?
Relugolix and norfloxacin can both lengthen the QT interval, so combining them may add to the risk of an abnormal heart rhythm; your care team can manage this by avoiding the combination when possible or monitoring your ECG and electrolytes. Keep taking both as prescribed and raise it with your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Norfloxacin 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 Norfloxacin interaction managed?
This interaction is usually manageable. Here is what a care team typically does and what you can do: Keep taking both as prescribed unless your prescriber tells you otherwise. Do not stop on your own. Your team may avoid using both together when there is a good alternative antibiotic. If both are needed, they may check an ECG and your blood electrolytes (potassium and magnesium) and correct any th… 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 Norfloxacin 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 Norfloxacin
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