Drug interactions
Desipramine + Promethazine
Severity: Major
Desipramine and Promethazine: major interaction.
Last updated Sources: US FDA label
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 desipramine can also produce anticholinergic effects and conduction abnormalities. Combination raises the risk of arrhythmia, particularly with electrolyte disturbances or heart disease, and promethazine is a CYP2D6 substrate while desipramine is a CYP2D6 substrate with modest inhibitory activity.
What this interaction means in plain words
Desipramine 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.
Desipramine belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Additive QT prolongation and sodium channel effects, plus additive sedative and anticholinergic effects.
What to do
Obtain a baseline ECG, correct potassium and magnesium, and avoid the combination in patients with QT risk factors. If used, monitor ECG and sedation and consider alternatives.
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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References
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 Desipramine
- Desipramine + Disopyramide Contraindicated
- Desipramine + Dofetilide Contraindicated
- Desipramine + Ibutilide Contraindicated
- Desipramine + Isocarboxazid Contraindicated
- Desipramine + Methylene blue Contraindicated
- Desipramine + Pentamidine Contraindicated
Frequently asked questions
Can I take Desipramine with Promethazine?
MediHelp rates the interaction as major. Desipramine 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 desipramine can also produce anticholinergic effects and conduction abnormalities. Combination raises the risk of arrhythmia, particularly with electrolyte disturbances or heart disease, and promethazine is a CYP2D6 substrate while desipramine is a CYP2D6 substrate with modest inhibitory activity.
How serious is the interaction between Desipramine 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: Obtain a baseline ECG, correct potassium and magnesium, and avoid the combination in patients with QT risk factors. If used, monitor ECG and sedation and consider alternatives.
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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