The earliest appearance of rash in the rash disease according to the disease manifested as different symptoms, common rash disease are chickenpox, measles, infantile emergency rash, scarlet fever, rubella and so on, different diseases, different manifestations. 1. Chickenpox: Rash appears on the 1st to 2nd day of fever, the first manifestation is red macula or papule, then it turns into blisters, and the base of the blisters is red. 2. Measles: the rash appears on the 3rd to 4th day of fever, the first rose-colored maculopapular rash, then the color deepens into dark red, and the pressure can fade. 3. Measles: the rash appears after 3-5 days of fever, characterized by heat and rash, the rash is red macular rash or maculopapular rash, which usually appears in one day and subsides on the next day. 4. Scarlet fever: the rash appears on the 1st to 2nd day of fever, which is red pinpoint spots or papules all over the body, and the color can fade away when pressed, and it is especially dense in the folds of the skin. 5. Rubella: rash on the first day of fever, the rash is red spots or papules, pressure can fade, mostly in about 3 days to disappear. Rash symptoms, should go to the hospital in time, under the guidance of the doctor for treatment, so as not to miss the condition.