Drug interactions
Clemastine + Olanzapine / samidorphan
Severity: Moderate
Clemastine 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
Both olanzapine and clemastine have anticholinergic activity, and combined use may increase constipation, urinary retention, dry mouth and in severe cases GI hypomotility. Additive sedation is also likely.
What this interaction means in plain words
Clemastine 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 antimuscarinic effects and additive CNS depression.
What to do
Monitor bowel function, urinary symptoms and sedation, and consider a non-sedating, non-anticholinergic antihistamine.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Clemastine and Olanzapine / samidorphan, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Clemastine
Frequently asked questions
Can I take Clemastine with Olanzapine / samidorphan?
MediHelp rates the interaction as moderate. Clemastine 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. Both olanzapine and clemastine have anticholinergic activity, and combined use may increase constipation, urinary retention, dry mouth and in severe cases GI hypomotility. Additive sedation is also likely.
How serious is the interaction between Clemastine 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 bowel function, urinary symptoms and sedation, and consider a non-sedating, non-anticholinergic antihistamine.
What other medicines interact with Clemastine?
MediHelp also lists interactions of Clemastine with, for example, Alfentanil, Benzhydrocodone / acetaminophen, Buprenorphine buccal. The full list is on the Clemastine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
