Ringworm is a skin disease caused by a fungal infection, which is called tinea cruris because the lesions occur in the groin, around the buttocks and the perineum. The danger of long term untreated ringworm is that on one hand it can cause further aggravation of the primary skin lesions, and on the other hand it may become self-infected, leading to fungal infections in other parts of the body. 1. causing aggravation of primary skin lesions: if ringworm is left untreated for a long period of time, the patient may scratch the skin lesions due to itching, which may lead to further aggravation of the primary skin infection. 2. Self-infection: Because fungi are contagious, long-term untreated ringworm may cause fungal infections in other parts of the body, such as tinea corporis, tinea cruris, or tinea capitis. For patients with ringworm, it is recommended to go to the regular hospital for examination and standardized treatment under the guidance of professional doctors.