Dehydration fever is a phenomenon in which the body (especially in pediatric patients), after severe dehydration, is affected by the decrease in water evaporation from the skin, which is the body’s heat dissipation, resulting in an increase in body temperature. When the room temperature is too high, the water evaporated from the skin of the newborn increases, the intake of breast milk is insufficient, and the blood is concentrated, and the body temperature can rise to 37.8-38.2 degrees in a short period of time without other conscious symptoms. Dehydration fever should be carefully differentiated from fever, medullary dehydration, and brain cell dehydration. 1.Fever A regulated increase in body temperature (more than 0.5℃) caused by the upward shift of the thermoregulatory point due to the action of pyrogen is called fever. Each person’s normal body temperature is slightly different and is affected by many factors (time, season, environment, menstruation, etc.). Therefore, the best way to determine if you have a fever is to compare it with your usual body temperature under the same conditions. If you do not know your original body temperature, an axillary body temperature (tested for 10 minutes) of more than 37.4°C can be defined as feverish. 2, nucleus pulposus dehydration Degeneration of the nucleus pulposus, mainly manifested as a decrease in water content and can cause small-scale pathological changes such as destabilization and loosening of the push joints due to water loss. After dehydration, the intervertebral disc loses its normal elasticity and tension, and on this basis, due to heavier trauma or repeated inconspicuous injuries, the fibrous ring is weakened or ruptured and the nucleus pulposus protrudes. 3.Brain cell dehydration When the increase of extracellular fluid osmolarity dehydrates brain cells, it can cause a series of symptoms of central nervous system dysfunction, including drowsiness, muscle twitching, coma, and even lead to death. It is hypertonic dehydration. When the brain volume is significantly reduced due to dehydration, the vascular tension between the skull and cerebral cortex increases, thus leading to local intracerebral hemorrhage and subarachnoid hemorrhage due to venous rupture. When the brain cells are dehydrated, they show impaired consciousness, irritability, cervical tonicity, and in severe cases, coracoacusis, myocardial tremor, and local or generalized convulsions. It even leaves sequelae. The capillary endothelial cells in brain tissue are closely connected with brain cells, and there is little interstitial presence between blood and brain, so when brain cells are dehydrated, water flows directly into the blood circulation. As the brain tissue is densely enclosed in the cranial cavity, brain cell crumpling can lower the cranial pressure, while the heart pumping pressure remains unchanged, which can result in cerebral vasodilation; in severe cases, it can cause cerebral hemorrhage or thrombosis.