Fever is a manifestation of the normal work of the body’s immune system, but if the fever persists, dehydration and acid-base balance disorders, febrile convulsions, cerebral edema and other bad things may occur. 1. Dehydration and acid-base balance disorders: patients with persistent fever is easy to cause dehydration, but also due to the use of antipyretic drugs a lot of sweat loss of water in the body, dehydration will be difficult to reduce fever, and will affect the metabolism and blood circulation. 2. Febrile convulsions: when the patient’s body temperature exceeds 39°C, the body is more sensitive to the inflammatory response caused by fever and convulsions. 3. Cerebral edema: when the patient’s body temperature exceeds 41°C when the fever is too high, it may cause protein decomposition in the body, forming cerebral edema, resulting in patients with cerebral sequelae. When the patient has a fever that does not go away, or even when the symptoms worsen, he should go to the hospital in time and receive standardized treatment under the guidance of the doctor, so as not to delay the condition.