Children always have a fever when they stop taking medicine. What's going on?

The child always has a cold. After stopping taking the medicine, he has a fever. This indicates that there is inflammation in the body. If the temperature is as high as 38.5 degrees, he needs to take ibuprofen to reduce the fever. If the temperature is lower than 38.5 degrees, he can wipe the body with warm water to reduce the fever.