Drug interactions
Erythromycin + Letermovir
Severity: Moderate
Erythromycin and Letermovir: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Letermovir inhibits CYP3A4 and OATP1B1/3 and may raise erythromycin levels, increasing its adverse effects such as QT prolongation. Erythromycin may in turn modestly raise letermovir levels through CYP3A and OATP inhibition.
What this interaction means in plain words
Erythromycin and Letermovir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Erythromycin belongs to Anti Bacterial; Letermovir belongs to Anti Virals.
Why it happens
Letermovir inhibits CYP3A4 and OATP1B1/3, reducing erythromycin clearance, while erythromycin inhibits CYP3A4 and OATP1B1/3 and can raise letermovir exposure.
What to do
Monitor for erythromycin toxicity, including ECG in patients with QT risk factors, and for letermovir adverse effects. Prefer an alternative antibiotic where possible.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin Contraindicated
Other interactions of Letermovir
- Ergotamine + Letermovir Contraindicated
- Letermovir + Pimozide Contraindicated
- Apalutamide + Letermovir Major
- Atorvastatin + Letermovir Major
- Carbamazepine + Letermovir Major
- Colchicine + Letermovir Major
Frequently asked questions
Can I take Erythromycin with Letermovir?
MediHelp rates the interaction as moderate. Erythromycin and Letermovir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Letermovir inhibits CYP3A4 and OATP1B1/3 and may raise erythromycin levels, increasing its adverse effects such as QT prolongation. Erythromycin may in turn modestly raise letermovir levels through CYP3A and OATP inhibition.
How serious is the interaction between Erythromycin and Letermovir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for erythromycin toxicity, including ECG in patients with QT risk factors, and for letermovir adverse effects. Prefer an alternative antibiotic where possible.
What other medicines interact with Erythromycin?
MediHelp also lists interactions of Erythromycin with, for example, Conivaptan, Dihydroergotamine intranasal, Dihydroergotamine. The full list is on the Erythromycin page.
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