A 3-year-old child with a fever and rash needs treatment. There are many causes of fever and rash in children such as allergies, immune deficiency or viral infections, and the treatments are different for different causes. 1. Allergy: If the rash is caused by allergy, the baby may also have itching. In addition to treating the baby’s fever, it is also necessary to give the baby anti-allergy drugs such as cetirizine hydrochloride, as well as identify the cause of the child’s allergy, to avoid the baby allergic again. 2. Immunity decline: children in the sick fever when the body’s immunity declined, the child may be thrombocytopenic purpura, the appearance of the rash is a blood-like rash, mild cases of children can be symptomatic treatment, severe cases need to go to the hospital after a detailed examination of platelet-boosting drugs such as immunoglobulin and other treatments. 3. Viral infection: If the child is a viral rash, you need to eat a light diet, avoid spicy food, etc., at the same time should be timely consultation. A 3-year-old child with a fever accompanied by a red rash, parents need to pay attention to, take the child to the hospital after examination, to identify the cause, under the guidance of the doctor to use drugs.