Ringworm on the back of the hand may be caused by fungal infection or psoriasis vulgaris, which requires reasonable medication according to the condition: 1. Fungal infection: It is more frequent in summer and autumn. It appears as thickened skin on the back of the hand, red patches with clear boundaries, itching, and peeling skin. Treatment requires oral antifungal drugs, such as itraconazole, and topical antifungal creams, which should be applied to an area larger than the area of the lesion. 2. Psoriasis vulgaris: psoriasis, a chronic inflammatory skin disease, can be treated with topical glucocorticosteroids and other drugs wiped on the affected area, as prescribed by the doctor, if the condition is serious. When ringworm grows on the back of the hand, patients should treat it in time to avoid aggravation of the condition, causing local skin breakage and infection.