Drug interactions
Amoxapine + Diphenhydramine
Severity: Moderate
Amoxapine and Diphenhydramine: 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 sedative and anticholinergic properties. Combining them can intensify drowsiness and anticholinergic effects such as dry mouth, urinary retention, constipation, confusion and tachycardia. Diphenhydramine also inhibits CYP2D6, which may raise amoxapine exposure.
What this interaction means in plain words
Amoxapine and Diphenhydramine 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 sedative effects, with possible CYP2D6 inhibition by diphenhydramine.
What to do
Monitor for oversedation and anticholinergic toxicity, and avoid the combination in elderly patients. Consider a non-sedating antihistamine instead.
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 Diphenhydramine
Frequently asked questions
Can I take Amoxapine with Diphenhydramine?
MediHelp rates the interaction as moderate. Amoxapine and Diphenhydramine 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 sedative and anticholinergic properties. Combining them can intensify drowsiness and anticholinergic effects such as dry mouth, urinary retention, constipation, confusion and tachycardia. Diphenhydramine also inhibits CYP2D6, which may raise amoxapine exposure.
How serious is the interaction between Amoxapine and Diphenhydramine?
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 elderly patients. Consider a non-sedating antihistamine instead.
What other medicines interact with Diphenhydramine?
MediHelp also lists interactions of Diphenhydramine with, for example, Alfentanil, Belladonna and opium, Benzhydrocodone / acetaminophen. The full list is on the Diphenhydramine page.
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