Is Black Cohosh Safe with Tamoxifen?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Consult your oncologist before taking Black Cohosh if prescribed Tamoxifen. Use is generally discouraged in hormone receptor-positive breast cancer patients due to uncertain estrogenic activity.
Why this interaction occurs
Black Cohosh exhibits selective estrogen receptor modulator (SERM)-like activity. Although its estrogenic mechanism is debated, it may interfere with Tamoxifen's estrogen receptor antagonism, potentially reducing its effectiveness in hormone receptor-positive breast cancer treatment.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 22,724 reports mentioning Tamoxifen. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Tamoxifen + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Black Cohosh interactions → · All Tamoxifen interactions →
Already checked this one — check your whole list
Educational only — not medical advice.
Always confirm with your doctor or pharmacist.