Drug interactions
Erythromycin ethylsuccinate + Promethazine
Severity: Major
Erythromycin ethylsuccinate 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 erythromycin ethylsuccinate can lead to an increased risk of QTc interval prolongation, which may result in serious cardiac arrhythmias. This interaction is particularly concerning in patients with pre-existing heart conditions or those taking other medications that also affect the QTc interval.
What this interaction means in plain words
Erythromycin ethylsuccinate 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.
Why it happens
Both drugs are known to influence cardiac repolarization, leading to an extended QTc interval. This effect can increase the risk of torsades de pointes, a potentially life-threatening arrhythmia.
What to do
Patients prescribed both medications should be closely monitored for signs of arrhythmia and consider alternative therapies. If co-administration is necessary, regular ECG monitoring may be warranted to assess QTc interval changes.
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
Frequently asked questions
Can I take Erythromycin ethylsuccinate with Promethazine?
MediHelp rates the interaction as major. Erythromycin ethylsuccinate 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 erythromycin ethylsuccinate can lead to an increased risk of QTc interval prolongation, which may result in serious cardiac arrhythmias. This interaction is particularly concerning in patients with pre-existing heart conditions or those taking other medications that also affect the QTc interval.
How serious is the interaction between Erythromycin ethylsuccinate 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: Patients prescribed both medications should be closely monitored for signs of arrhythmia and consider alternative therapies. If co-administration is necessary, regular ECG monitoring may be warranted to assess QTc interval changes.
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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