Drug interactions
Amitriptyline + Promethazine
Severity: Moderate
Amitriptyline and Promethazine: moderate 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 cause sedation and have anticholinergic effects, and both can prolong the QT interval. The combination may increase drowsiness, confusion, urinary retention and arrhythmia risk.
What this interaction means in plain words
Amitriptyline and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Amitriptyline belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Additive CNS depression, anticholinergic activity and QT prolongation.
What to do
Monitor sedation and anticholinergic effects, and check ECG and electrolytes in patients with cardiac risk factors. Prefer an alternative if QT risk is high.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Amitriptyline
- Amitriptyline + Isocarboxazid Contraindicated
- Amitriptyline + Methylene blue Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amitriptyline + Procarbazine Contraindicated
- Amitriptyline + Safinamide Contraindicated
Frequently asked questions
Can I take Amitriptyline with Promethazine?
MediHelp rates the interaction as moderate. Amitriptyline and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Both drugs cause sedation and have anticholinergic effects, and both can prolong the QT interval. The combination may increase drowsiness, confusion, urinary retention and arrhythmia risk.
How serious is the interaction between Amitriptyline and Promethazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor sedation and anticholinergic effects, and check ECG and electrolytes in patients with cardiac risk factors. Prefer an alternative if QT risk is high.
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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