Drug interactions
Erythromycin + Protriptyline
Severity: Moderate
Erythromycin and Protriptyline: 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
Both drugs can prolong the QT interval, raising the risk of torsades de pointes. Erythromycin may also modestly raise tricyclic levels via CYP3A4 inhibition, adding to anticholinergic and cardiac effects.
What this interaction means in plain words
Erythromycin and Protriptyline 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
Additive QT prolongation, with possible CYP inhibition by erythromycin raising tricyclic exposure.
What to do
Consider a non-macrolide antibiotic. If combined, obtain an ECG and correct electrolytes, and monitor for tricyclic toxicity.
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
Frequently asked questions
Can I take Erythromycin with Protriptyline?
MediHelp rates the interaction as moderate. Erythromycin and Protriptyline 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. Both drugs can prolong the QT interval, raising the risk of torsades de pointes. Erythromycin may also modestly raise tricyclic levels via CYP3A4 inhibition, adding to anticholinergic and cardiac effects.
How serious is the interaction between Erythromycin and Protriptyline?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider a non-macrolide antibiotic. If combined, obtain an ECG and correct electrolytes, and monitor for tricyclic toxicity.
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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