Drug interactions
Maprotiline + Promethazine
Severity: Major
Maprotiline 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
Both drugs can prolong the QT interval and cause sedation and anticholinergic effects, so combined use raises arrhythmia risk and impairs alertness. Maprotiline also lowers the seizure threshold, which promethazine may further affect.
What this interaction means in plain words
Maprotiline 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.
Maprotiline belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Additive QT prolongation, anticholinergic effects and CNS depression; both can lower seizure threshold.
What to do
Avoid the combination where possible, especially with other QT risk factors; if needed, obtain a baseline ECG, correct potassium and magnesium, and monitor for arrhythmia, sedation and seizures.
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
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Other interactions of Maprotiline
- Arsenic trioxide + Maprotiline Contraindicated
- Disopyramide + Maprotiline Contraindicated
- Dofetilide + Maprotiline Contraindicated
- Ibutilide + Maprotiline Contraindicated
- Isocarboxazid + Maprotiline Contraindicated
- Maprotiline + Methylene blue Contraindicated
Frequently asked questions
Can I take Maprotiline with Promethazine?
MediHelp rates the interaction as major. Maprotiline 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. Both drugs can prolong the QT interval and cause sedation and anticholinergic effects, so combined use raises arrhythmia risk and impairs alertness. Maprotiline also lowers the seizure threshold, which promethazine may further affect.
How serious is the interaction between Maprotiline 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: Avoid the combination where possible, especially with other QT risk factors; if needed, obtain a baseline ECG, correct potassium and magnesium, and monitor for arrhythmia, sedation and seizures.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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