Drug interactions
Erythromycin ethylsuccinate + Tamoxifen
Severity: Minor
Erythromycin ethylsuccinate 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 may slow the conversion of tamoxifen to N-desmethyltamoxifen and raise tamoxifen concentrations. Because N-desmethyltamoxifen is converted to the more potent endoxifen mainly by CYP2D6, the net clinical effect is modest and not well characterised.
What this interaction means in plain words
Erythromycin ethylsuccinate 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.
Why it happens
Erythromycin inhibits CYP3A4-mediated N-demethylation of tamoxifen.
What to do
No routine dose change is needed; be aware of the interaction if tamoxifen toxicity or reduced response is suspected. Consider an alternative antibiotic such as azithromycin during prolonged courses.
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 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 ethylsuccinate with Tamoxifen?
MediHelp rates the interaction as minor. Erythromycin ethylsuccinate 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 may slow the conversion of tamoxifen to N-desmethyltamoxifen and raise tamoxifen concentrations. Because N-desmethyltamoxifen is converted to the more potent endoxifen mainly by CYP2D6, the net clinical effect is modest and not well characterised.
How serious is the interaction between Erythromycin ethylsuccinate 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 dose change is needed; be aware of the interaction if tamoxifen toxicity or reduced response is suspected. Consider an alternative antibiotic such as azithromycin during prolonged courses.
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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