Relugolix and Erythromycin: 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
Erythromycin
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.
Let's talk about taking relugolix (Orgovyx) and the antibiotic erythromycin together. Erythromycin can block a transporter that helps clear relugolix from your body, so more relugolix can build up. That may raise the chance of side effects.
On top of that, both drugs can affect your heart's electrical timing (called the QT interval), and together they may nudge it further, which in rare cases can cause irregular heartbeats. The good news is your care team knows how to handle this. They can adjust timing, watch you more closely, and check your heart and electrolytes if needed. Please don't stop either medicine on your own, just talk with your pharmacist or doctor.
Effect: Erythromycin (P-gp inhibitor) may increase relugolix (P-gp substrate) exposure, raising adverse-reaction risk; both agents also prolong the QT interval, giving additive PD effects.
Direction: Increased relugolix exposure. Evidence: theoretical. Onset: unspecified. Severity: major.
- Avoid concomitant use where possible.
- If unavoidable: give relugolix first, separate dosing by at least 6 hours, monitor more frequently.
- Relugolix may be interrupted up to 2 weeks for a short erythromycin course; if held greater than 7 days, restart with 360 mg loading dose, then 120 mg daily.
- Correct electrolytes; consider periodic ECG and electrolyte monitoring, especially with long QT syndrome, CHF, or electrolyte abnormalities.
What happens
Increased relugolix exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Do not combine relugolix, which is a P-gp substrate, with P-gp inhibitors, since doing so can raise relugolix exposure and thereby heighten the likelihood of adverse reactions. When such combined use cannot be avoided, give the relugolix-containing medication first, keep the two doses at least 6 hours apart, and increase the frequency of monitoring for adverse reactions12. Relugolix therapy may be paused for as long as 2 weeks to allow a brief course of P-gp inhibitor treatment. Restart relugolix once the P-gp inhibitor has been stopped. Should relugolix be withheld for more than 7 days, reinitiate it using a 360 mg loading dose on the first day, followed by 120 mg once daily thereafter1. When relugolix is given together with drugs that prolong the QT interval, the effects on the QT interval may be additive. In patients who have congenital long QT syndrome, congestive heart failure, or frequent electrolyte abnormalities, as well as those on drugs recognized to prolong the QT interval, weigh whether the benefits of androgen deprivation therapy such as relugolix outweigh the possible risks. Correct any electrolyte abnormalities and consider periodically monitoring ECGs and electrolytes1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of relugolix; additive QT interval prolongation
How to manage this interaction
Your care team has clear ways to manage this combination:
- Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise.
- Your team may avoid the combination or, if erythromycin is needed, separate the doses by at least 6 hours (taking relugolix first) and watch you more closely.
- Sometimes relugolix may be paused during a short antibiotic course and resumed afterward; your team will guide any dose adjustment and individualize it for you.
- They may check your electrolytes and heart rhythm (ECG), especially if you have heart-rhythm history.
Ask your pharmacist or prescriber before starting any new medicine, and mention any dizziness, fainting, or palpitations.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) Giving relugolix (a P-gp substrate) together with erythromycin (a P-gp and CYP3A inhibitor) raised relugolix's AUC by 3.5-fold and its Cmax by 2.9-fold, respectively 1.
Common questions
Can I take Relugolix and Erythromycin together?
Combining erythromycin with relugolix can raise relugolix levels and add to QT-prolongation risk; keep taking both as prescribed but let your care team decide on spacing doses, monitoring, or an alternative antibiotic. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Relugolix and Erythromycin 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 Erythromycin interaction managed?
Your care team has clear ways to manage this combination: Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise. Your team may avoid the combination or, if erythromycin is needed, separate the doses by at least 6 hours (taking relugolix first) and watch you more closely. Sometimes relugolix may be paused during a short antibiotic course and resumed afterward; your tea… 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 Erythromycin 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 (2)
- Product Information: ORGOVYX oral tablets, relugolix oral tablets. Sumitomo Pharma America, Inc (per FDA), Marlborough, MA, 2025. DailyMed
- Product Information: MYFEMBREE(R) oral tablets, relugolix, estradiol, norethindrone acetate oral tablets. Myovant Sciences Inc (per FDA), Brisbane, CA, 2021. DailyMed
Keep reading about Erythromycin
Keep reading about Relugolix
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