When a child develops a fever again 3 days after the fever has subsided, it is likely that the fever again and the previous fever are two causes. After the first fever, the child’s body resistance is often weak, and it takes longer to recover. During the recovery period, the resistance is weaker, and it is easy for bacterial or viral infections to occur, leading to fever, so there is a situation where the child has a fever again 3 days after the fever has subsided. The first step is to check the child’s blood count, C-reactive protein and antibodies to Mycoplasma pneumoniae to confirm whether the fever is caused by an infection or not. If an infection does exist, you need to choose the appropriate medication for anti-inflammatory treatment depending on the type of infection. If the temperature is high, above 38.5 degrees, you also need to use antipyretic drugs to be more effective, and oral ibuprofen suspension is recommended. Bacterial infections require antibiotics, and in the case of Mycoplasma pneumoniae infection, azithromycin can be used.