The red patches on the calves may be caused by contact dermatitis, eczema, ringworm, etc. They can be treated with mometasone furoate cream, hassinide cream, dianabed cream, tretinoin cream, clotrimazole cream, terbinafine hydrochloride cream, and so on. 1. Contact dermatitis: is due to contact with external allergens lead to skin, mucous membrane inflammatory reaction, there will be a clear border of erythema, itching and other symptoms, broken with vesicles, oozing and other phenomena, should be avoided in a timely manner to contact with the allergic substances, can be through the mometasone furoate cream, hassinade cream and other medications for treatment. 2. Eczema: It is an inflammatory reaction of the superficial dermis and epidermis caused by many factors, which will cause red spots and itching. Symptoms can be improved by medicines such as Dinocapnemide cream and Tretinoin cream. 3. Ringworm: It is a skin disease caused by fungal infection, and the common causative fungi are Trichophyton rubrum, Trichophyton mustelii, etc. In the early stage of skin lesions, there will be red pimples. Early lesions will appear red papules, with the development of the disease will appear scaly red patches, this patch border clear, accompanied by different degrees of itching. It can be treated with drugs such as clotrimazole cream and terbinafine hydrochloride cream. Therefore, patients with long red plaques on the calves that itch like crazy should go to the hospital as soon as possible to clarify the cause of the disease, and actively cooperate with the doctor to carry out symptomatic treatment after diagnosis.