Drug interactions
Grapefruit + Tamoxifen
Severity: Minor
Grapefruit 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
Grapefruit inhibits intestinal CYP3A4 and might slightly alter tamoxifen metabolism to N-desmethyltamoxifen. No meaningful clinical effect has been established.
What this interaction means in plain words
Grapefruit 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.
Why it happens
Grapefruit furanocoumarins inhibit intestinal CYP3A4.
What to do
No restriction is generally needed; moderate grapefruit intake is acceptable.
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
Frequently asked questions
Can I take Grapefruit with Tamoxifen?
MediHelp rates the interaction as minor. Grapefruit 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. Grapefruit inhibits intestinal CYP3A4 and might slightly alter tamoxifen metabolism to N-desmethyltamoxifen. No meaningful clinical effect has been established.
How serious is the interaction between Grapefruit 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 restriction is generally needed; moderate grapefruit intake is acceptable.
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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