What happens when a man takes the Pill? Well, most oral contraceptives are made of the hormones oestrogen and progestin (or progesterone), found in the biological makeup of women. So, if a man takes the Pill for a period of time, he may develop larger breasts, less facial hair, smaller testicles, and a decreased sex drive.

Reference: http://www.maineteenhealth.org/faqs/what-happens-if-a-guy-takes-a-birth-control-pill/