Drug interactions
Clarithromycin + Erythromycin base
Severity: Major
Clarithromycin and Erythromycin base: major interaction.
Last updated Sources: US FDA label
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
Two macrolides taken together add QT-prolonging effects and offer no therapeutic benefit. Both inhibit CYP3A4, so exposure to each may increase, raising the risk of arrhythmia and adverse effects.
What this interaction means in plain words
Clarithromycin and Erythromycin base can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive QT prolongation and mutual CYP3A4 inhibition.
What to do
Avoid concurrent use of two macrolides and choose a single agent appropriate to the infection.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
Frequently asked questions
Can I take Clarithromycin with Erythromycin base?
MediHelp rates the interaction as major. Clarithromycin and Erythromycin base can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Two macrolides taken together add QT-prolonging effects and offer no therapeutic benefit. Both inhibit CYP3A4, so exposure to each may increase, raising the risk of arrhythmia and adverse effects.
How serious is the interaction between Clarithromycin and Erythromycin base?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid concurrent use of two macrolides and choose a single agent appropriate to the infection.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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