Men taking progesterone breasts will develop, but they are deformed. Under the joint action of progesterone and estrogen, it can promote the development of breasts. And the sex hormones in a man’s body are mainly androgens, with only a small amount of estrogen. If a man takes a relatively small amount of progesterone, the effect is not great. If a man takes progesterone in excess for a long time, it may cause breast development, such as breast enlargement, which is a deformed development of the breast. If a man takes progesterone for a long time and in large quantities, it may also affect the secondary sexual characteristics, such as not growing a beard, the knot in the throat becomes smaller, erectile dysfunction or hypogonadism, etc., and even the endocrine will be abnormal, leading to the emergence of some diseases. Therefore, if it is not necessary to treat the disease, it is not recommended that men take progesterone without authorization, so as to avoid serious side effects, which is also not conducive to men’s health.