Drug interactions
Haloperidol + Promazine
Severity: Major
Haloperidol 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 phenothiazine and butyrophenone antipsychotics prolong the QT interval, so combining them increases the risk of torsades de pointes. They also add to sedation, anticholinergic and extrapyramidal effects.
What this interaction means in plain words
Haloperidol 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 hERG channel blockade causing QT prolongation, with additive dopamine antagonism.
What to do
Avoid concurrent antipsychotics where possible and use monotherapy. If combined, 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 Haloperidol
- Dofetilide + Haloperidol Contraindicated
- Dronedarone + Haloperidol Contraindicated
- Haloperidol + Ibutilide Contraindicated
- Haloperidol + Levoketoconazole Contraindicated
- Haloperidol + Panobinostat Contraindicated
- Haloperidol + Pimozide Contraindicated
Frequently asked questions
Can I take Haloperidol with Promazine?
MediHelp rates the interaction as major. Haloperidol 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 phenothiazine and butyrophenone antipsychotics prolong the QT interval, so combining them increases the risk of torsades de pointes. They also add to sedation, anticholinergic and extrapyramidal effects.
How serious is the interaction between Haloperidol 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 antipsychotics where possible and use monotherapy. If combined, monitor ECG and electrolytes.
What other medicines interact with Haloperidol?
MediHelp also lists interactions of Haloperidol with, for example, Dofetilide, Dronedarone, Ibutilide. The full list is on the Haloperidol page.
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