Adults with fever and red rashes on the body may be related to herpes zoster, pityriasis rosea, and drug rash. 1. Herpes zoster: It may be that the varicella-zoster virus latent in the patient’s body is activated when the patient develops low immunity. When the virus reaches the area of nerve distribution, it will cause localized skin reactions, initially with fever and corn-sized red rash. 2. pityriasis rosea: generally associated with human herpes virus infection, while cellular immune response is also involved in this disease. The invasion of the virus causes the body to develop fever as well as a red rash. 3. Drug Rash: It may be the first time that the patient uses certain drugs such as ciprofloxacin and penicillin. There may be a sudden onset of fever accompanied by red papules of rice grain size. Adults with fever rash can also be seen in other causes, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions for relevant examinations, with the help of the doctor to clarify the nature, and targeted treatment or treatment.