How long it takes for gynecomastia to subside depends on which type it belongs to. There are three types of gynecomastia: the first one is infantile gynecomastia, that is, newborn babies, no matter they are male or female, boys or girls, will have breast development after birth or within one or two weeks after birth, and you don’t need to be too nervous about it, it is caused by the estrogen in the mother. This is due to the development of breasts caused by estrogen in the mother’s body, which does not need to be treated, and will usually subside gradually within a week or two after birth, or if it doesn’t, you need to go to the hospital. The second type of breast development is pubertal breast development, it is mostly due to endocrine disorders during puberty causing transient breast development, as long as the symptoms are not obvious, you can leave it alone, and it will usually subside in about one or two years. The third type of breast development is the breast development of middle-aged and old people, the cause of which is still unclear, and most of them need to be treated with medication, which is effective and can usually subside in one or two months. In addition, for the unknown cause of breast development, do not be careless, need to further examination, especially for obese or hepatitis some men, often drinking men, may be due to hepatitis or cirrhosis of the liver caused by the liver’s inactivation of estrogen ability to decline, caused by the body of estrogen increase, which in turn cause breast development, this need to find out the cause of the disease for symptomatic treatment.