Many diseases can lead to a rash, such as some rash diseases such as measles, rubella, hand, foot and mouth disease, early childhood emergency rash, most of which are caused by viral infections, may or may not be accompanied by fever, the baby is in good spirits, the blood test routine white blood cells are reduced or in normal, C-reactive protein is normal, you can give antiviral treatment, such as oral four seasons antiviral combination, pediatric pharyngeal flat punch and other observations. If the fever is accompanied by a small bright red rash on the trunk of the body, enlarged tonsils and a prune tongue, and increased leukocytes and C-reactive protein, the fever is usually scarlet fever, which is caused by bacterial infection, and antibiotic treatment should be given. If the rash is windy and itchy, most of them are caused by allergies, and oral anti-allergy drugs such as paracetamol and vitamin C can be given.