The red rash on the body after fever in children may be due to Kawasaki disease, infantile acute rash, scarlet fever and other diseases. 1. Kawasaki disease: Kawasaki disease, also known as pediatric cutaneous mucocutaneous lymph node syndrome, may be related to infection, immunity, genetics and other factors, the child may have fever, rash, rash is polymorphic erythema-like, accompanied by perianal skin redness, desquamation. 2. Childhood emergency rash: Childhood emergency rash is caused by viral infections, children can show high fever lasting 3~5 days after the temperature dropped suddenly, heat rash, rash is light red macular rash or maculopapular rash, scattered distribution, to the trunk, buttocks, distal limbs, sparse, 1~2 days after the subside, subside after no obvious pigmentation. 3. Scarlet fever: Scarlet fever is an acute respiratory infectious disease caused by group A beta streptococcus. Children with scarlet fever may present with fever, pharyngitis, diffuse bright red rash all over the body, and post-rash desquamation. The rash is a diffuse hemorrhagic pinpoint-sized papule, which starts from the back of the ear, the neck, and the upper chest, and then spreads all over the body rapidly. In addition to the diseases listed above, hand-foot-mouth disease, measles, rubella, chickenpox and other diseases can also appear after the fever with a red rash on the body, please consult the doctor in time to avoid delaying the condition.