Drug interactions
Clarithromycin + Promethazine
Severity: Major
Clarithromycin and Promethazine: major 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
The concurrent use of promethazine and clarithromycin can lead to an increased risk of QT interval prolongation, which may result in serious cardiac arrhythmias. Patients taking both medications should be monitored closely for signs of cardiac issues, especially if they have pre-existing heart conditions.
What this interaction means in plain words
Clarithromycin and Promethazine 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; Promethazine belongs to Respiratory.
Why it happens
Both drugs are known to affect cardiac repolarization, leading to an increased QTc interval. This effect can enhance the risk of torsades de pointes, a potentially life-threatening arrhythmia.
What to do
It is advisable to avoid co-administration of these medications whenever possible. If their use together is necessary, continuous ECG monitoring should be implemented to detect any significant changes in heart rhythm.
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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Other interactions of Promethazine
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine 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 Promethazine?
MediHelp rates the interaction as major. Clarithromycin and Promethazine 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. The concurrent use of promethazine and clarithromycin can lead to an increased risk of QT interval prolongation, which may result in serious cardiac arrhythmias. Patients taking both medications should be monitored closely for signs of cardiac issues, especially if they have pre-existing heart conditions.
How serious is the interaction between Clarithromycin and Promethazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: It is advisable to avoid co-administration of these medications whenever possible. If their use together is necessary, continuous ECG monitoring should be implemented to detect any significant changes in heart rhythm.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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