Men with erythema on the inner thighs have a variety of clinical possibilities, such as ringworm, eczema-like dermatitis, infection, etc., as follows: 1, ringworm: the most common, if the inflammatory reaction of ringworm is more obvious, there may be local erythema, and it occurs symmetrically; 2, eczema-like dermatitis: especially due to allergies or local sweat impregnation, or due to local irritants leading to metaplasia changes, there will also be erythema-like reaction, this time may be accompanied by a certain degree of itching, some people may also be accompanied by a certain degree of pain symptoms; 3, infection: especially bacterial infection formed by local skin soft tissue inflammation, this time may also appear local erythema, pain and limited edema, etc., some people may also be accompanied by a certain degree of general discomfort or fever, etc.