Drug interactions
Clarithromycin + Formoterol
Severity: Major
Clarithromycin and Formoterol: 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
Clarithromycin prolongs the QT interval and formoterol can add to this through tachycardia and hypokalemia. The combination increases the risk of torsades de pointes, particularly with other risk factors.
What this interaction means in plain words
Clarithromycin and Formoterol 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.
Clarithromycin belongs to Anti Bacterial; Formoterol belongs to Respiratory.
Why it happens
Additive QT prolongation, with beta-2 agonist-induced hypokalemia increasing proarrhythmic risk.
What to do
Consider a non-macrolide antibiotic such as amoxicillin or doxycycline where appropriate. If combined, check electrolytes and monitor the ECG.
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 Formoterol
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
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 Formoterol?
MediHelp rates the interaction as major. Clarithromycin and Formoterol 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. Clarithromycin prolongs the QT interval and formoterol can add to this through tachycardia and hypokalemia. The combination increases the risk of torsades de pointes, particularly with other risk factors.
How serious is the interaction between Clarithromycin and Formoterol?
MediHelp rates it major, 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 such as amoxicillin or doxycycline where appropriate. If combined, check electrolytes and monitor the ECG.
What other medicines interact with Formoterol?
MediHelp also lists interactions of Formoterol with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Formoterol page.
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