Drug interactions
Lofepramine + Promethazine
Severity: Moderate
Lofepramine 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 promethazine and the tricyclic antidepressant lofepramine can prolong the QT interval and have anticholinergic and sedative effects. The combination increases the risk of ventricular arrhythmias, especially with electrolyte disturbance or cardiac disease. Additive sedation and anticholinergic burden are also expected.
What this interaction means in plain words
Lofepramine 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.
Why it happens
Additive QT prolongation and additive anticholinergic and sedative effects.
What to do
Avoid in patients with QT risk factors and consider an alternative antiemetic or antihistamine. If used together, monitor ECG and electrolytes and watch for excess sedation.
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
Frequently asked questions
Can I take Lofepramine with Promethazine?
MediHelp rates the interaction as moderate. Lofepramine 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 promethazine and the tricyclic antidepressant lofepramine can prolong the QT interval and have anticholinergic and sedative effects. The combination increases the risk of ventricular arrhythmias, especially with electrolyte disturbance or cardiac disease. Additive sedation and anticholinergic burden are also expected.
How serious is the interaction between Lofepramine 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: Avoid in patients with QT risk factors and consider an alternative antiemetic or antihistamine. If used together, monitor ECG and electrolytes and watch for excess sedation.
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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