Drug interactions
Letermovir + Tamoxifen
Severity: Moderate
Letermovir and Tamoxifen: 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 is a moderate CYP3A inhibitor and may raise tamoxifen concentrations. Letermovir also induces CYP2C9/2C19, so the net effect on active metabolites is uncertain.
What this interaction means in plain words
Letermovir and Tamoxifen 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 belongs to Anti Virals; Tamoxifen belongs to Endocrine.
Why it happens
Letermovir inhibits CYP3A4, reducing tamoxifen metabolism.
What to do
Monitor for tamoxifen adverse effects during letermovir prophylaxis. No empirical dose change is recommended.
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 Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
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 Letermovir with Tamoxifen?
MediHelp rates the interaction as moderate. Letermovir and Tamoxifen 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 is a moderate CYP3A inhibitor and may raise tamoxifen concentrations. Letermovir also induces CYP2C9/2C19, so the net effect on active metabolites is uncertain.
How serious is the interaction between Letermovir and Tamoxifen?
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 tamoxifen adverse effects during letermovir prophylaxis. No empirical dose change is recommended.
What other medicines interact with Tamoxifen?
MediHelp also lists interactions of Tamoxifen with, for example, Amiodarone, Anastrozole, Bupropion. The full list is on the Tamoxifen page.
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