Drug interactions
Erythromycin + Tamoxifen
Severity: Minor
Erythromycin and Tamoxifen: minor 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
Erythromycin inhibits CYP3A4, which converts tamoxifen to N-desmethyltamoxifen, and may alter tamoxifen metabolite profile. Because N-desmethyltamoxifen is a precursor of the active metabolite endoxifen via CYP2D6, the clinical effect is uncertain and likely small.
What this interaction means in plain words
Erythromycin and Tamoxifen have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Erythromycin belongs to Anti Bacterial; Tamoxifen belongs to Endocrine.
Why it happens
CYP3A4 inhibition by erythromycin reduces tamoxifen N-demethylation.
What to do
No routine adjustment is needed; use for the shortest necessary course. Prefer an alternative antibiotic if prolonged macrolide therapy is required.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
Frequently asked questions
Can I take Erythromycin with Tamoxifen?
MediHelp rates the interaction as minor. Erythromycin and Tamoxifen have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Erythromycin inhibits CYP3A4, which converts tamoxifen to N-desmethyltamoxifen, and may alter tamoxifen metabolite profile. Because N-desmethyltamoxifen is a precursor of the active metabolite endoxifen via CYP2D6, the clinical effect is uncertain and likely small.
How serious is the interaction between Erythromycin and Tamoxifen?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine adjustment is needed; use for the shortest necessary course. Prefer an alternative antibiotic if prolonged macrolide therapy is required.
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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