Drug interactions
Diphenhydramine + Marijuana
Severity: Moderate
Diphenhydramine and Marijuana: 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 produces sedation, impaired cognition and slowed reaction time, and diphenhydramine adds to these effects. Both may also contribute to tachycardia or dizziness.
What this interaction means in plain words
Diphenhydramine and Marijuana 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 depressant effects.
What to do
Counsel patients to avoid driving and hazardous activities when using both. Prefer a non-sedating 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 Diphenhydramine and Marijuana, 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 Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Marijuana?
MediHelp rates the interaction as moderate. Diphenhydramine and Marijuana 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 produces sedation, impaired cognition and slowed reaction time, and diphenhydramine adds to these effects. Both may also contribute to tachycardia or dizziness.
How serious is the interaction between Diphenhydramine and Marijuana?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Counsel patients to avoid driving and hazardous activities when using both. Prefer a non-sedating antihistamine.
What other medicines interact with Diphenhydramine?
MediHelp also lists interactions of Diphenhydramine with, for example, Alfentanil, Belladonna and opium, Benzhydrocodone / acetaminophen. The full list is on the Diphenhydramine 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.
