Drug interactions
Erythromycin base + Oxybutynin
Severity: Moderate
Erythromycin base and Oxybutynin: 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
Erythromycin inhibits CYP3A4 in the liver and gut wall, which can raise oxybutynin concentrations, particularly with the immediate-release oral form. This may intensify anticholinergic adverse effects such as dry mouth, constipation, confusion and urinary retention.
What this interaction means in plain words
Erythromycin base and Oxybutynin 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.
Why it happens
Inhibition of CYP3A4-mediated first-pass and hepatic metabolism of oxybutynin.
What to do
Monitor for increased anticholinergic effects and reduce the oxybutynin dose if they develop; consider an alternative antibiotic in frail patients.
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 Oxybutynin
Frequently asked questions
Can I take Erythromycin base with Oxybutynin?
MediHelp rates the interaction as moderate. Erythromycin base and Oxybutynin 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 inhibits CYP3A4 in the liver and gut wall, which can raise oxybutynin concentrations, particularly with the immediate-release oral form. This may intensify anticholinergic adverse effects such as dry mouth, constipation, confusion and urinary retention.
How serious is the interaction between Erythromycin base and Oxybutynin?
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 increased anticholinergic effects and reduce the oxybutynin dose if they develop; consider an alternative antibiotic in frail patients.
What other medicines interact with Oxybutynin?
MediHelp also lists interactions of Oxybutynin with, for example, Bethanechol, Clozapine, Potassium chloride. The full list is on the Oxybutynin page.
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