Drug interactions
Doxylamine + Olanzapine / samidorphan
Severity: Moderate
Doxylamine and Olanzapine / samidorphan: 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
Olanzapine is sedating and can cause orthostatic hypotension, and doxylamine adds sedative and anticholinergic effects. Together they may increase drowsiness, dizziness, falls, constipation and urinary retention.
What this interaction means in plain words
Doxylamine and Olanzapine / samidorphan 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 CNS depression and anticholinergic activity from H1, muscarinic and other receptor blockade.
What to do
Monitor for sedation, orthostatic hypotension and anticholinergic effects. Avoid regular doxylamine use in older patients on olanzapine.
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 Doxylamine
Frequently asked questions
Can I take Doxylamine with Olanzapine / samidorphan?
MediHelp rates the interaction as moderate. Doxylamine and Olanzapine / samidorphan 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. Olanzapine is sedating and can cause orthostatic hypotension, and doxylamine adds sedative and anticholinergic effects. Together they may increase drowsiness, dizziness, falls, constipation and urinary retention.
How serious is the interaction between Doxylamine and Olanzapine / samidorphan?
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 sedation, orthostatic hypotension and anticholinergic effects. Avoid regular doxylamine use in older patients on olanzapine.
What other medicines interact with Doxylamine?
MediHelp also lists interactions of Doxylamine with, for example, Belladonna and opium, Benzhydrocodone / acetaminophen, Brexanolone. The full list is on the Doxylamine page.
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