Drug interactions
Marijuana + Olanzapine
Severity: Moderate
Marijuana 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
Cannabis can add to olanzapine's sedation and impair cognition and psychomotor performance. It may also cause tachycardia and orthostatic hypotension, and it can worsen psychosis in susceptible patients, which counteracts olanzapine's therapeutic aim.
What this interaction means in plain words
Marijuana 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.
Why it happens
Additive CNS depression plus cannabinoid-related psychotomimetic and cardiovascular effects; smoked cannabis may also induce CYP1A2, lowering olanzapine levels.
What to do
Advise patients to avoid cannabis, and monitor sedation, heart rate, blood pressure and psychiatric symptoms. Assess for reduced olanzapine response in regular smokers.
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
Frequently asked questions
Can I take Marijuana with Olanzapine?
MediHelp rates the interaction as moderate. Marijuana 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. Cannabis can add to olanzapine's sedation and impair cognition and psychomotor performance. It may also cause tachycardia and orthostatic hypotension, and it can worsen psychosis in susceptible patients, which counteracts olanzapine's therapeutic aim.
How serious is the interaction between Marijuana 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 cannabis, and monitor sedation, heart rate, blood pressure and psychiatric symptoms. Assess for reduced olanzapine response in regular smokers.
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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