Drug interactions
Promethazine + Propantheline
Severity: Moderate
Promethazine and Propantheline: 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 have antimuscarinic effects. Combined use may cause pronounced dry mouth, constipation, urinary retention, blurred vision, tachycardia and confusion, particularly in older adults.
What this interaction means in plain words
Promethazine and Propantheline 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 antimuscarinic effects.
What to do
Monitor for anticholinergic toxicity and reduce doses or choose a less anticholinergic option if it occurs. Use caution in glaucoma, urinary obstruction and ileus.
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 Promethazine with Propantheline?
MediHelp rates the interaction as moderate. Promethazine and Propantheline 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 have antimuscarinic effects. Combined use may cause pronounced dry mouth, constipation, urinary retention, blurred vision, tachycardia and confusion, particularly in older adults.
How serious is the interaction between Promethazine and Propantheline?
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 for anticholinergic toxicity and reduce doses or choose a less anticholinergic option if it occurs. Use caution in glaucoma, urinary obstruction and ileus.
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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