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Can other drugs interfere with hormone therapy?
Source: Hormone Therapy for Breast Cancer, National Cancer Institute.
Source updated: December 2, 2025 · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary. Independent clinical review is pending.
NCI patient treatment article for this disease Exact source article; not a clinically reviewed indication or current-standard recommendation.
Context: Hormone Therapy for Breast Cancer
Can other drugs interfere with hormone therapy?
Some types of antidepressants can reduce the effectiveness of tamoxifen. This can be an issue because some people with breast cancer have clinical depression and/or hot flashes that are treated with antidepressants.
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If you take an antidepressant, talk with your doctor about whether it will reduce the effectiveness of tamoxifen. If so, you may want to discuss switching to a different antidepressant before beginning tamoxifen. Antidepressants that doctors may recommend for people taking tamoxifen include sertraline, citalopram, and venlafaxine.
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If you are postmenopausal and taking an antidepressant that reduces tamoxifen’s effectiveness, your doctor may suggest taking an aromatase inhibitor instead of tamoxifen.
Other medications that could interfere with tamoxifen include:
quinidine, which is used to treat abnormal heart rhythms
diphenhydramine, which is an antihistamine
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cimetidine, which is used to reduce stomach acid
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You should discuss with your doctor all medicines you are currently taking before you start taking tamoxifen.
Preserved source evidence · Independent clinical review pending · Not medical advice