livstrong explains what happens, Side Effects of Men Taking Female Birth Control Pills Female birth control pills are intended to prevent contraception in women. They are most often a combination of synthetic forms of both types of female hormones, estrogen and progesterone. Although rarely used, female hormones may be taken by men for a number of medical conditions such as prostate enlargement, testicular cancer and aromatase deficience. Because oral contraceptives are not intended for use in men, side effects have not been well studied or documented; however, they may cause a number of adverse effects in men similar to those seen with the use of other female hormones. Testosterone is responsible for the formation and development of male sex characteristics. When testosterone is opposed by high levels of female hormones present in birth control pills, testosterone will be less effective. Men who take female birth controls may experience changes in the functioning and physical appearance of their sex organs. Risks may include lowered sperm count, decreased libido, erectile dysfunction and shrinking testes size. Some men may also develop breast tissue, known as gynecomastia, along with enlargement and darkening of the nipples.