Drug interactions
Diphenhydramine + Risperidone
Severity: Moderate
Diphenhydramine and Risperidone: 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, so combined use can produce marked drowsiness and impaired psychomotor performance. Diphenhydramine's anticholinergic activity adds to that of risperidone and may cause confusion, urinary retention or constipation. Diphenhydramine also modestly inhibits CYP2D6, which may raise risperidone exposure.
What this interaction means in plain words
Diphenhydramine and Risperidone 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.
Diphenhydramine belongs to Respiratory; Risperidone belongs to Central Nervous System.
Why it happens
Additive CNS depression and anticholinergic effects, with possible CYP2D6 inhibition by diphenhydramine increasing risperidone levels.
What to do
Monitor for oversedation, anticholinergic effects and extrapyramidal symptoms, particularly in older adults. Prefer a non-sedating antihistamine when feasible.
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 Risperidone
- Ibutilide + Risperidone Contraindicated
- Risperidone + Vandetanib Contraindicated
- Adagrasib + Risperidone Major
- Amiodarone + Risperidone Major
- Amisulpride + Risperidone Major
- Amoxapine + Risperidone Major
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Risperidone?
MediHelp rates the interaction as moderate. Diphenhydramine and Risperidone 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, so combined use can produce marked drowsiness and impaired psychomotor performance. Diphenhydramine's anticholinergic activity adds to that of risperidone and may cause confusion, urinary retention or constipation. Diphenhydramine also modestly inhibits CYP2D6, which may raise risperidone exposure.
How serious is the interaction between Diphenhydramine and Risperidone?
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, anticholinergic effects and extrapyramidal symptoms, particularly in older adults. Prefer a non-sedating antihistamine when feasible.
What other medicines interact with Risperidone?
MediHelp also lists interactions of Risperidone with, for example, Ibutilide, Vandetanib, Adagrasib. The full list is on the Risperidone page.
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