High fever usually has no sequelae, complications can be reviewed to check the relevant indicators or according to the cause of the disease. After the fever goes down, there may be dehydration, the process of fever reduction will sweat, taking away part of the water and electrolytes, pay attention to replenish fluids and electrolytes, can review the blood routine, electrolytes and so on. If the fever is complicated by heart failure, brain natriuretic peptide and cardiac ultrasound can be reviewed. If the fever is caused by infections, check the blood routine, CRP, calcitoninogen and other inflammatory indexes; if the central nervous system is involved and the fever is long, it may damage the brain nerves, so check the electroencephalogram regularly; if the fever is caused by certain tumors, treat the primary disease actively, and check the tumor markers, CT or magnetic resonance imaging regularly. Fever for a long time more than 41 ℃, the protein in the body may be decomposed, causing cerebral edema and cause disease, may leave sequelae of encephalopathy, can check the EEG, cranial MRI to understand the damage. If the fever causes discomfort, consult a doctor in time to find out the cause of the disease and make a clear diagnosis, and do not take medication without authorization, so as not to cause adverse consequences.