Drug interactions
Diphenhydramine + Loxapine
Severity: Moderate
Diphenhydramine and Loxapine: 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
Diphenhydramine is strongly sedating and anticholinergic, and loxapine adds its own sedative and antimuscarinic effects. The combination may cause marked drowsiness, confusion, urinary retention, constipation and impaired cognition, especially in the elderly. Diphenhydramine is also sometimes used to treat loxapine-induced extrapyramidal symptoms, but with added anticholinergic burden.
What this interaction means in plain words
Diphenhydramine and Loxapine 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; Loxapine belongs to Central Nervous System.
Why it happens
Additive CNS depression and antimuscarinic activity from H1 and muscarinic receptor blockade.
What to do
Use the lowest effective diphenhydramine dose and warn about sedation. Monitor for anticholinergic toxicity and avoid in elderly or cognitively impaired patients where possible.
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 Loxapine
- Alfentanil + Loxapine Major
- Alprazolam + Loxapine Major
- Amisulpride + Loxapine Major
- Amoxapine + Loxapine Major
- Apomorphine + Loxapine Major
- Belladonna and opium + Loxapine Major
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Loxapine?
MediHelp rates the interaction as moderate. Diphenhydramine and Loxapine 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 is strongly sedating and anticholinergic, and loxapine adds its own sedative and antimuscarinic effects. The combination may cause marked drowsiness, confusion, urinary retention, constipation and impaired cognition, especially in the elderly. Diphenhydramine is also sometimes used to treat loxapine-induced extrapyramidal symptoms, but with added anticholinergic burden.
How serious is the interaction between Diphenhydramine and Loxapine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use the lowest effective diphenhydramine dose and warn about sedation. Monitor for anticholinergic toxicity and avoid in elderly or cognitively impaired patients where possible.
What other medicines interact with Loxapine?
MediHelp also lists interactions of Loxapine with, for example, Alfentanil, Alprazolam, Amisulpride. The full list is on the Loxapine page.
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