Usually, skin diseases are mostly related to physical and chemical stimuli, bacterial and viral infections, allergies, internal diseases and other factors, and have little to do with sex. However, it should be noted that if unclean sex occurs, after infection of sexually transmitted diseases, there will also be a variety of skin manifestations, such as infection of syphilis in the early stages, the external genitalia will appear cartilaginous ulcers; infection of warts, the periphery of the genitalia will grow a variety of forms of redundant organisms; infection of HIV, the body localized patchy rashes; infection of the herpes simplex virus, a large number of blisters appeared on the external genitalia, and so on. In addition, some people are allergic to semen, after having sex, the skin will also have some allergic reactions, such as growing red pimples and so on.