The causes of dark spots usually include seborrheic keratosis, post-inflammatory hyperpigmentation and skin melanosis, etc., which need to be treated by doctors in time once discovered. 1. Seborrheic keratosis: it may be related to genetic factors, skin aging, viral infection, excessive exposure to sunlight or medication, and it is a common benign tumor of epidermis. 2. Post-inflammatory hyperpigmentation: it is due to the inflammatory reaction to reduce the sulfhydryl groups in the skin, thus weakening the inhibitory effect of tyrosinase to a certain extent, so that its activity increases leading to the deepening of local pigmentation appearing dark spots. 3. Skin melanosis: it may be related to excessive exposure to ingredients containing tar or photosensitizing substances in the working and living environment, which eventually leads to skin melanosis. The appearance of dark spots may also be caused by other reasons, and it is recommended that patients go to the hospital in time to consult the doctor to clarify the cause of the disease and then standardize the treatment under the doctor’s guidance.