Repeated itching of the back may be caused by allergic dermatitis or pruritus. If it is caused by allergies, the most common reason is related to the bedding you wear, whether there are mites in the bedding or not, and whether there is laundry detergent in the clothes you wear or not, etc. Allergic dermatitis is more common. Repeated itching of the back may also be pruritus. If you are older, your body function declines, nutritional disorders occur, and your body function cannot adjust to the drastic changes in the external environment, which can cause pruritus. It is recommended to go to the dermatology department of the hospital for diagnosis and treatment. Do not eat spicy stimulation, do not eat seafood, fish and shrimp and other easily allergic ingredients.