The itching on the back is considered to be the following: 1. pruritus, a disease caused by excessive dryness of the skin and thinning of the sebaceous film resulting in small breaks on the skin surface, mostly occurring in middle-aged and elderly people. 2. eczema, in addition to itching, can also see erythema, papules, blisters, papules and other polymorphic rash manifestations, due to allergy to sunlight and ultraviolet radiation, or contact with chemical clothing products. 3. The rash is caused by allergy due to sunlight and ultraviolet radiation, or contact with chemical clothing products, or allergic reactions due to the consumption of large amounts of fishy and hairy products, such as seafood, beef and mutton, chicken, duck, goose and dog meat, etc. 3, may be due to the corresponding symptoms of erythematous scaling diseases, such as psoriasis due to genetics, infection, trauma and other factors.