Ringworm at the base of the thighs is medically known as tinea cruris and is often caused by the same part of the fungal infection as tinea pedis. The fungus grows more easily in warm, humid environments, so ringworm tends to occur in the summer. Ringworm occurs more often in men, and the occurrence of ringworm usually results in localized erythema and papules, flaking, and itching. The treatment is similar to that of tinea pedis, and both require the use of antifungal medications such as topical ketoconazole, miconazole nitrate, which is what the common people call dacronin, and terbinafine, cypionamide, etc. All of these creams are more effective. If the lesions are large and develop into the buttocks and the itching is more intense, you can take oral antifungal medications like itraconazole and ketoconazole to treat it. Ringworm is important for prevention, and in the presence of tinea pedis, socks and underwear need to be washed separately to keep the area dry, clean, and breathable, etc., to effectively prevent its occurrence.