Drug interactions
Lapatinib + Marijuana
Severity: Minor
Lapatinib and Marijuana: minor 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
Cannabidiol in cannabis can inhibit CYP3A4 and may raise lapatinib exposure. Effects depend on product and dose and are poorly characterized.
What this interaction means in plain words
Lapatinib and Marijuana have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Cannabinoids, especially cannabidiol, inhibit CYP3A4 in vitro, which may reduce lapatinib metabolism.
What to do
Ask patients about cannabis use and monitor for lapatinib adverse effects such as diarrhea and liver changes.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Frequently asked questions
Can I take Lapatinib with Marijuana?
MediHelp rates the interaction as minor. Lapatinib and Marijuana have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Cannabidiol in cannabis can inhibit CYP3A4 and may raise lapatinib exposure. Effects depend on product and dose and are poorly characterized.
How serious is the interaction between Lapatinib and Marijuana?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Ask patients about cannabis use and monitor for lapatinib adverse effects such as diarrhea and liver changes.
What other medicines interact with Lapatinib?
MediHelp also lists interactions of Lapatinib with, for example, Dofetilide, Ibutilide, Pimozide. The full list is on the Lapatinib page.
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