Tinea cruris is a skin disease caused by fungal infection of the inner femur, perineum, and buttocks. The pathogens that cause ringworm in our country are mainly Trichophyton rubrum and Trichophyton rubrum plasteri of the genus Trichophyton, Flocculina epidermidis of the genus Trichophyton, and a few Candida albicans. The main symptom is significant localized itching. The disease is prone to recurrence. It is more common in men than in women. The disease tends to occur in summer and is often aggravated by humid or hot climates, and remits or heals in winter. The diagnosis of ringworm is usually easy to confirm based on clinical symptoms and fungal microscopy. Self-diagnosis points: If you find ring-shaped or semi-ring-shaped erythema with clear borders and flaking on the inner thighs, buttocks, etc., you need to exclude the possibility of ringworm. It is recommended to consult a regular hospital nearby to confirm the diagnosis. Points to note: Try to avoid the use of dermatitis and other hormonal creams, which can cause the condition to move repeatedly.