The present invention provides methods for treating and preventinggynecomastia by administering 4-hydroxy tamoxifen to a patient. Whenpercutaneously administered to a patient's breasts, 4-hydroxy tamoxifenconcentrates locally, and exerts an anti-estrogenic effect. In patients withgynecomastia, this reduces the effective estrogen-androgen ratio in the breasttissue, thereby reducing ductal proliferation, epithelial and stromalhyperplasia, and pain. In patients at risk for developing gynecomastia, 4-hydroxy tamoxifen's anti-estrogenic effect prevents tissue proliferation andits accompanying pain.
