For itchy skin, physical examination, allergen testing, dermoscopy and skin testing are required. 1. Visual examination: The first step is to examine the number, shape, size, color, elasticity and other basic conditions of the skin lesions through visual examination. 2. Allergen testing: Allergen testing can assist in the diagnosis of most allergic dermatoses and clarify the allergens. 3. Dermoscopy: Skin infectious diseases (such as ringworm, scabies, pubic lice), skin inflammatory diseases (such as psoriasis, eczema) and other skin diseases can be detected by dermoscopy. 4. Skin test: patch test can be used for the auxiliary diagnosis of skin contact dermatitis, scratch test can be used for the diagnosis of urticaria. If the itchy skin can not be relieved, it is recommended to go to the hospital in a timely manner, do the relevant examination for targeted treatment.