Telithromycin and Relugolix: 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
Telithromycin
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.
Let me explain what happens when telithromycin (an antibiotic) is taken with relugolix (Orgovyx, used for prostate cancer). Telithromycin can block a transporter in your body that normally helps clear relugolix out. This can let relugolix build up to higher levels, which may mean more side effects.
On top of that, both medicines can affect your heart's rhythm (something called QT prolongation). Taken together, that effect can add up. This is based mostly on how the drugs work rather than lots of real-world reports, but it's still worth taking seriously. The good news: your care team can manage this by adjusting timing, watching you more closely, and checking your heart tracing and lab values.
Effect: Increased relugolix exposure plus additive QT prolongation risk.
Mechanism: Telithromycin inhibits P-gp, reducing efflux of relugolix (a P-gp substrate), raising its plasma concentrations. Both agents independently prolong the QT interval, giving additive cardiac risk. Neither is a prodrug here. Evidence is theoretical; severity major.
- Avoid concomitant use where possible.
- If unavoidable: give relugolix first, separate doses by at least 6 hours, monitor for adverse reactions.
- Relugolix may be interrupted up to 2 weeks for short P-gp inhibitor courses; if held >7 days, restart with 360 mg loading dose then 120 mg daily.
- Correct electrolytes; consider periodic ECG and electrolyte monitoring, especially with baseline QT risk.
What happens
Increased relugolix exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Because relugolix is a P-gp substrate, using it together with P-gp inhibitors should be avoided, since this combination can raise relugolix exposure and thereby heighten the likelihood of adverse reactions. When coadministration cannot be avoided, give the relugolix-containing product first, allow a gap of at least 6 hours between doses, and increase the frequency of monitoring for adverse reactions12. Relugolix therapy may be paused for as long as 2 weeks to accommodate a brief course of a P-gp inhibitor, with relugolix resumed once the P-gp inhibitor has been stopped. Should relugolix be withheld for more than 7 days, it should be reinitiated using a loading dose of 360 mg on day one, followed by 120 mg once daily thereafter1. Giving relugolix alongside medications that prolong the QT interval can produce additive effects on 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 to prolong the QT interval, weigh whether the benefits of androgen deprivation therapy such as relugolix outweigh the possible risks. Electrolyte abnormalities should be corrected, and periodic monitoring of ECGs and electrolytes should be considered1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of relugolix; additive QT interval prolongation
How to manage this interaction
Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. This combination is usually avoided when possible, but if you need both, your team has clear ways to manage it.
- They may have you take your relugolix dose first and space it at least 6 hours from the antibiotic.
- They may watch you more closely for side effects.
- They may check your heart tracing (ECG) and blood electrolytes, and correct any imbalances.
- Because telithromycin is often a short course, your relugolix may be paused and restarted afterward, sometimes with a loading dose your prescriber will set.
Ask your pharmacist or doctor before starting, stopping, or changing anything, and report dizziness, fainting, or palpitations.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) When relugolix (a P-gp substrate) was given together with erythromycin (a P-gp and CYP3A inhibitor), the AUC of relugolix rose by 3.5-fold and its Cmax rose by 2.9-fold 1.
Common questions
Can I take Telithromycin and Relugolix together?
Combining telithromycin with relugolix can raise relugolix levels and add to heart-rhythm (QT) risk, so it is generally avoided; if both are needed, your care team will separate the doses, monitor you closely, and may check ECGs and electrolytes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Telithromycin and Relugolix 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 Telithromycin and Relugolix interaction managed?
Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. This combination is usually avoided when possible, but if you need both, your team has clear ways to manage it. They may have you take your relugolix dose first and space it at least 6 hours from the antibiotic. They may watch you more closely for side effects. They may check your heart tracing (ECG) and bl… 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 Telithromycin or Relugolix 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 Telithromycin
Keep reading about Relugolix
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