Tinea cruris is caused by a fungal infection. The initial factor of the disease is the attachment of fungus at the root of the thigh. Without timely and effective treatment, the fungus reproduces more and more, and the affected area expands, which might develop to the buttocks or even other parts of the body. Therefore, once it occurs, proper treatment is essential. Commonly used antifungal creams can completely cure it if applied long-term. During treatment, it is important to regulate dietary and lifestyle habits, avoid public baths, swimming, and use separate bath towels and scrubbing towels. Patients with athlete's foot must wash their socks and underwear separately, ensure thorough sun exposure and disinfection, eat a light diet, bathe more frequently, and keep the affected area dry.