Itchy rash is an inflammatory skin disease characterized by itching. The cause of the disease has not been fully clarified, and it is considered to be related to food, environment, heredity, and other diseases. 1. Food: clearly known allergens, such as fish and shrimp, pollen or certain medications, contact with the above allergy-inducing substances may lead to the appearance of itchy, doughnut-like papules on the skin. 2. Environment: Poor hygiene and malnutrition may trigger itchy rash. 3. Heredity: patients with a family history of itchy rash, such as patients whose parents suffer from itchy rash, affected by genetic factors, their children are more likely to suffer from the disease. 4. Other diseases: gastrointestinal dysfunction, anemia, endocrine disease or other diseases may induce itchy rash. Skin with obvious itching sensation, it is recommended to pay attention to daily care, do not scratch the stimulus, to avoid inducing infection, you can go to the hospital dermatology department, under the guidance of the doctor treatment.