Drug interactions
Doxylamine + Olanzapine
Severity: Moderate
Doxylamine and Olanzapine: 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
Doxylamine is a strongly sedating antihistamine, so combined use with olanzapine can cause heavy drowsiness and impaired alertness. Additive anticholinergic effects may produce confusion, dry mouth, constipation and urinary retention.
What this interaction means in plain words
Doxylamine and Olanzapine 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.
Doxylamine belongs to Respiratory; Olanzapine belongs to Central Nervous System.
Why it happens
Additive CNS depression through H1 blockade, plus additive antimuscarinic effects.
What to do
Advise avoiding driving and alcohol, and avoid use in older adults where possible. Choose a non-sedating alternative if an antihistamine is needed.
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 Olanzapine
Other interactions of Doxylamine
Frequently asked questions
Can I take Doxylamine with Olanzapine?
MediHelp rates the interaction as moderate. Doxylamine and Olanzapine 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. Doxylamine is a strongly sedating antihistamine, so combined use with olanzapine can cause heavy drowsiness and impaired alertness. Additive anticholinergic effects may produce confusion, dry mouth, constipation and urinary retention.
How serious is the interaction between Doxylamine and Olanzapine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise avoiding driving and alcohol, and avoid use in older adults where possible. Choose a non-sedating alternative if an antihistamine is needed.
What other medicines interact with Olanzapine?
MediHelp also lists interactions of Olanzapine with, for example, Amisulpride, Amoxapine, Apomorphine. The full list is on the Olanzapine page.
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