Drug interactions
Orphenadrin + Promethazine
Severity: Moderate
Orphenadrin 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
Promethazine is strongly sedating and anticholinergic, and orphenadrine adds to both effects. The combination can cause marked drowsiness, confusion, urinary retention and tachycardia, with higher risk in older adults.
What this interaction means in plain words
Orphenadrin 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.
Orphenadrin belongs to Musculoskeletal; Promethazine belongs to Respiratory.
Why it happens
Additive central nervous system depression and muscarinic receptor blockade.
What to do
Monitor for oversedation and anticholinergic toxicity, and avoid the combination in older adults where possible. Counsel to avoid driving and alcohol.
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 Orphenadrin
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 Orphenadrin with Promethazine?
MediHelp rates the interaction as moderate. Orphenadrin 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. Promethazine is strongly sedating and anticholinergic, and orphenadrine adds to both effects. The combination can cause marked drowsiness, confusion, urinary retention and tachycardia, with higher risk in older adults.
How serious is the interaction between Orphenadrin 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 oversedation and anticholinergic toxicity, and avoid the combination in older adults where possible. Counsel to avoid driving and alcohol.
What other medicines interact with Orphenadrin?
MediHelp also lists interactions of Orphenadrin with, for example, Alfentanil, Amobarbital, Benzhydrocodone / acetaminophen. The full list is on the Orphenadrin page.
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