Tinea inguinalis is ringworm. Tinea cruris is a fungal infection of the skin in the groin, perineum, perianal area and buttocks. It is mainly caused by fungal infections such as Trichophyton rubrum, Trichophyton spp., Trichophyton verrucosum, and Microsporum canis. It begins as a red papule, blister or herpetiform rash, followed by a flaky red patch with clear borders and gradually spreading edges in all directions, and patients can relieve their symptoms with medication and daily care. Patients can be treated with topical imidazole antifungal drugs such as ketoconazole ointment and acrylamide antifungal drugs such as terbinafine under the guidance of professional doctors. If the lesions expand and spread to involve the lower abdomen and buttocks, oral itraconazole can be taken for a short period of time. If symptoms such as increased skin temperature and pus exudation occur, it indicates the presence of secondary bacterial infection, and internal antibacterial drugs can be taken as prescribed by the doctor. The medication should be administered in sufficient quantity and duration to prevent and control recurrence, and be reviewed regularly. During the treatment process, patients should keep the affected skin clean and dry, use loose and breathable underwear, and avoid sweat impregnation. Do not scratch the affected area to prevent self-infection and secondary infection. Patients should use separate towels and bath towels to avoid infections to others.