4 years old baby fever 40 degrees dangerous?

Hello, according to your description, your 4-year-old baby has a fever of 40 degrees, this is still a very high degree, it is still quite dangerous for the baby, I suggest you take some antipyretic drugs as soon as possible, otherwise continue to develop, it will cause very bad effects on the baby's central nervous system, you can take some antipyretic drugs such as Merrill Lynch orally, the effect is faster, but must be used according to the instructions, but also always observe the baby's temperature, first every half hour measurement, At the same time pay attention to observe the baby's mental state, if lethargy or listlessness, to go to the hospital in time to see a doctor.