Red rashes in children with fever may be caused by diseases such as early childhood emergency rash, rubella, scarlet fever, or other diseases such as chickenpox. 1. Childhood emergency rash: The pathogenesis of childhood emergency rash is not yet clear, and it is considered to be caused by human herpesvirus type 6 infection. The child will have fever, rash, convulsions and other symptoms, and also have a runny nose, sore throat, cough and other symptoms. 2. Rubella: Rubella is mainly caused by rubella virus infection, and the main symptoms are fever, rash, cough and sore throat. In addition, children with rubella will also have symptoms such as swollen lymph nodes and conjunctival congestion. 3. Scarlet fever: Scarlet fever is mainly caused by group A β-hemolytic streptococcus infection, and children with scarlet fever mainly have fever, rash, sore throat, headache, vomiting and other symptoms. 4. Other: Chickenpox and other diseases can also lead to the phenomenon of children with fever and red rash. Children with fever and red rash may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.