Drug interactions
Cannabidiol + Tamoxifen
Severity: Minor
Cannabidiol and Tamoxifen: 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 inhibits several CYP enzymes in vitro, including CYP2C9, CYP3A4 and CYP2D6, and could alter tamoxifen and metabolite concentrations. Clinical relevance is unproven.
What this interaction means in plain words
Cannabidiol and Tamoxifen 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 belongs to Central Nervous System; Tamoxifen belongs to Endocrine.
Why it happens
Inhibition of CYP enzymes involved in tamoxifen metabolism, potentially changing formation of active metabolites.
What to do
No routine dose change is needed. Monitor for tamoxifen adverse effects and treatment response if cannabidiol is used regularly.
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 Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
Other interactions of Cannabidiol
- Cannabidiol + Phenytoin Major
- Cannabidiol + Sodium valproate Major
- Cannabidiol + Tacrolimus Major
- Abiraterone + Cannabidiol Moderate
- Alogliptin-pioglitazone + Cannabidiol Moderate
- Amiodarone + Cannabidiol Moderate
Frequently asked questions
Can I take Cannabidiol with Tamoxifen?
MediHelp rates the interaction as minor. Cannabidiol and Tamoxifen 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 inhibits several CYP enzymes in vitro, including CYP2C9, CYP3A4 and CYP2D6, and could alter tamoxifen and metabolite concentrations. Clinical relevance is unproven.
How serious is the interaction between Cannabidiol and Tamoxifen?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine dose change is needed. Monitor for tamoxifen adverse effects and treatment response if cannabidiol is used regularly.
What other medicines interact with Tamoxifen?
MediHelp also lists interactions of Tamoxifen with, for example, Amiodarone, Anastrozole, Bupropion. The full list is on the Tamoxifen page.
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