Drug interactions
Orphenadrine + Promethazine
Severity: Moderate
Orphenadrine 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 are sedating and strongly anticholinergic. Combined use can cause marked drowsiness, confusion, dry mouth, blurred vision, constipation and urinary retention, particularly in older patients.
What this interaction means in plain words
Orphenadrine 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 antimuscarinic and CNS depressant effects.
What to do
Monitor for anticholinergic toxicity and oversedation, and use lower doses in older adults. Consider an alternative to one of the agents if confusion or retention develops.
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 Orphenadrine with Promethazine?
MediHelp rates the interaction as moderate. Orphenadrine 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 are sedating and strongly anticholinergic. Combined use can cause marked drowsiness, confusion, dry mouth, blurred vision, constipation and urinary retention, particularly in older patients.
How serious is the interaction between Orphenadrine 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 for anticholinergic toxicity and oversedation, and use lower doses in older adults. Consider an alternative to one of the agents if confusion or retention develops.
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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