Hair or manhood—choose one?

In ancient Greece, Hippocrates and Aristotle observed that eunuchs did not go bald. Jumping ahead to the early 1940s, American anatomist James B. Hamilton reviewed histories of men with testosterone deficiency and found a pattern: the earlier the age of hormone deficiency, the less balding occurred.

Research review: Alterations to penile and prostatic tissue associated with finasteride and dutasteride treatment

Simple summary: Numerous studies have shown that treatment with finasteride and dutasteride can change the size, tissue composition and function of the prostate and penis. Changes in the penis linked to finasteride or dutasteride treatment include: reduced size and weight; reduced erectile response; decreased smooth muscle; increased collagen density; fibrosis (scarring or other tissue abnormalities); … Read more