Drug interactions
Chlorpromazine + Promazine
Severity: Major
Chlorpromazine and Promazine: 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
Both are phenothiazine antipsychotics with QT-prolonging potential, so combining them adds to arrhythmia risk and also duplicates anticholinergic, sedative and hypotensive effects. There is rarely a reason to use two drugs of the same class together.
What this interaction means in plain words
Chlorpromazine and Promazine 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 blockade of cardiac hERG potassium channels causing QT prolongation, plus duplicated dopaminergic, anticholinergic and alpha-adrenergic blockade.
What to do
Avoid concurrent use and consolidate to a single phenothiazine at the lowest effective dose. If overlap occurs during switching, monitor ECG and electrolytes.
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 Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat Contraindicated
Frequently asked questions
Can I take Chlorpromazine with Promazine?
MediHelp rates the interaction as major. Chlorpromazine and Promazine 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. Both are phenothiazine antipsychotics with QT-prolonging potential, so combining them adds to arrhythmia risk and also duplicates anticholinergic, sedative and hypotensive effects. There is rarely a reason to use two drugs of the same class together.
How serious is the interaction between Chlorpromazine and Promazine?
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 and consolidate to a single phenothiazine at the lowest effective dose. If overlap occurs during switching, monitor ECG and electrolytes.
What other medicines interact with Chlorpromazine?
MediHelp also lists interactions of Chlorpromazine with, for example, Dofetilide, Dronedarone, Droperidol. The full list is on the Chlorpromazine page.
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