Self-injury often occurs for the first time in adolescence. The current classification distinguishes several groups: (1) factitious disorder imposed on self and factitious disorder imposed on another, (2) nonsuicidal self-injury (NSSI) and (3) obsessive–compulsive (OCD) and related disorders. The differential diagnosis includes a wide spectrum of psychiatric diseases, including borderline personality disorder (BPD), inherited disorders like Lesch–Nyhan syndrome (LNS) and also body modifications. In all these cases, self-harm is a subphenomenon. This review focuses on typical dermatological pictures.