A sudden rise in body temperature to 39 degrees is likely to be accompanied by fear of cold or even chills, otherwise the temperature should not be a sudden rise. If there are no chills, the temperature is likely to rise slowly. When it reaches 39 degrees, it will be accompanied by more obvious discomfort. At this time, you can apply antipyretic drugs according to the temperature and the corresponding accompanying symptoms. After applying antipyretic and anti-inflammatory drugs such as ibuprofen, the body temperature will be lowered later, and the performance of lowering is sweating, and after lowering, the body temperature is lowered and the accompanying symptoms can be relieved. If the body temperature rises to such a high level, it is a more serious inflammatory reaction, and the vast majority of them are infections. You can look for the foci of infection by the accompanying symptoms of fever and whether there is coughing, coughing, frequent urination, urgent urination or abdominal pain and diarrhea, etc. If there is corresponding evidence to suggest this, you should conduct relevant examinations for further confirmation.