In general, dark nipples may be caused by normal physiological phenomena, pregnancy or some diseases. 1. Normal physiological phenomenon: Whether male or female, in general, the nipple and areola pigmentation is more obvious, compared with other parts of the body, the skin is slightly darker, which is a normal phenomenon. 2. Pregnancy: If the patient is a woman, in the stage of pregnancy, the body’s estrogen level rises, causing breast duct hyperplasia and hyperpigmentation, which may lead to black nipples. After the breastfeeding period is over, the hormone level in the body will restore the balance, and the color of the nipple will subside. 3. Some diseases: male or female patients who suffer from thyroid disease, pituitary gland disease or adrenal gland disease will lead to endocrine imbalance and hormonal changes in the body, resulting in black nipples. At the same time, conditions such as nipple cancer and recurrent eczema around the nipple may also cause the nipple to appear dark. If the patient’s nipples are uncomfortable, it is recommended to consult a regular hospital in time and choose the appropriate treatment under the guidance of the doctor.