Drug interactions
Clemastine + Olanzapine
Severity: Moderate
Clemastine 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
Taking these together can increase drowsiness, slow reaction times and impair concentration. Additive anticholinergic effects can also cause constipation, urinary retention, dry mouth and confusion, particularly in older adults.
What this interaction means in plain words
Clemastine 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.
Clemastine belongs to Respiratory; Olanzapine belongs to Central Nervous System.
Why it happens
Additive CNS depression via H1 blockade, plus additive antimuscarinic effects.
What to do
Advise patients to avoid driving or hazardous tasks until response is known. Prefer a non-sedating antihistamine, especially in the elderly.
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 Clemastine
Frequently asked questions
Can I take Clemastine with Olanzapine?
MediHelp rates the interaction as moderate. Clemastine 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. Taking these together can increase drowsiness, slow reaction times and impair concentration. Additive anticholinergic effects can also cause constipation, urinary retention, dry mouth and confusion, particularly in older adults.
How serious is the interaction between Clemastine 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 patients to avoid driving or hazardous tasks until response is known. Prefer a non-sedating antihistamine, especially in the elderly.
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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