Tinea crurus is a superficial fungal infection that occurs in the pubic area or at the base of the thighs. It is most common in warm and humid seasons, and can recur in the summer when it becomes milder or fades in winter, with a high incidence in obese or sweaty people. The erythema may expand outward, gradually forming a semi-ring-shaped lesion with a purplish-red color and raised edges in a circular pattern. The lesions are usually formed by the spread of tinea capitis, but are also associated with contact with diseased animals (e.g., cats and dogs), poor hygiene habits, and weak body resistance. People who take adrenocorticosteroids for a long time, diabetics, and people with chronic wasting diseases are also susceptible. In the past, the treatment of ringworm was based on the use of topical antifungals. Currently, 1+1 therapy is advocated, which involves taking one antifungal medication internally plus an antifungal agent. For mild cases, external antifungal agents can be applied; for those with extensive, significant inflammation, poor efficacy of external agents, or immunocompromised conditions, oral antifungal agents such as itraconazole, fluconazole, and terbinafine can be administered. With regular treatment under the guidance of a doctor, ringworm is completely cured.