Fever after vaccination is a common systemic adverse reaction to vaccination. Generally, the fever caused by vaccination appears within 24 hours after vaccination, and the duration of fever is usually 1-2 days. If your child develops a fever at night after vaccination, first of all we need to see what the temperature is. If the temperature is below 38.5℃ and the mental state is relatively good, with no other symptoms such as crying or rash, we can observe the child first and give him or her an antipyretic patch and some hot water, and his or her temperature will probably come down. If the temperature exceeds 38.5℃ and the child’s mental state is not good, we can give the child some antipyretic medication at this time, you can take oral treatment of Merrill Lynch or ibuprofen, the specific dosage based on the weight of the child according to the instructions to eat. You can also use acetaminophen antipyretic suppositories to treat the anus, and at the same time, use warm water to wipe the body, drink more hot water, can help to lower the temperature. If the fever does not go down for more than 48 hours, you need to go to the hospital to find the cause of the fever.