Blackening at the anus is a relatively common clinical phenomenon, which will gradually darken with age, mostly due to hyperpigmentation. If there is no itching or special symptoms, it is a normal physiological phenomenon, and there is no need to apply special drugs or methods to intervene, and it can be observed clinically. For some blackening of the anus with swelling or eczema-like changes, it is possible to consider the possibility of infectious molluscum contagiosum or anal eczema. An applied ointment, such as the common eutrophiles and interferon ointments, can be applied to treat molluscum contagiosum. For the more serious ones, they can also be completely eradicated by laser surgery or liquid nitrogen freezing. The actual anal darkening is usually a good idea to go to a regular hospital for a detailed examination. You can go to the dermatology department for the appropriate examination to find the exact cause of the problem and take the appropriate treatment plan.