Itchy skin may be caused by eczema, urticaria, contact dermatitis, insect bite dermatitis, diabetes and other factors. 1. Eczema: caused by a combination of internal and external factors, can be manifested as erythema, papules, scales, ooze and other symptoms, mostly accompanied by itching, easy to recur, never heal. 2. Urticaria: commonly known as “rubella block”, is caused by a variety of foods, drugs or other factors that stimulate the skin, manifested in different sizes, doughnut-shaped elevations, bright red or pale white, with obvious itching. 3. Contact dermatitis: due to contact with bees, pollen, soap and other exogenous substances, skin inflammatory reaction, usually the scope of dermatitis and contact with the material is generally consistent with the manifestation of erythema, edema, papules, and other symptoms, border is clearer, the patient is often self-conscious of the itching, burning, swelling and pain. 4. Insect bite dermatitis: is due to insect bites local skin allergies and inflammatory reactions occurring after the skin, commonly in the waist, buttocks, limbs and other exposed parts, manifested as a sudden occurrence of pea to the size of a finger doughnut erythema, often accompanied by a huge itch. 5. Diabetes mellitus: diabetic peripheral neuropathy, may also lead to symptoms of itchy skin, mostly occurring in both upper limbs, both lower limbs, distal to the main, and to the night itching. There are many other factors that lead to itchy skin, it is recommended that patients seek medical attention in a timely manner in order to clarify the cause of the disease, targeted treatment.