The main symptoms of dehydration include thirst and weakness, dry mouth, dry skin, indentation, decreased elasticity, and in severe cases, there may be consciousness disorders. Dehydration is a series of clinical syndromes in which the reduction of water in the body due to various causes causes metabolic disorders. The main pathophysiologic changes are changes in blood sodium and osmolality. According to osmolality, it can be divided into hypotonic, isotonic and hypertonic dehydration; according to blood sodium concentration, it can be divided into mild, moderate and severe dehydration. Clinical manifestations: mild can have dizziness, fatigue, weakness, etc.; moderate dehydration can have dry mouth and tongue, dry skin, depression, decreased elasticity, increased heart rate, urine, etc.; severe dehydration can have shock, coma, loss of reflexes, impaired consciousness, etc., which can be life-threatening. At the same time, dehydration can also be accompanied by etiologic symptoms. Severe dehydration without timely and effective treatment can also lead to death. When there are symptoms of thirst, please replenish water in time, and if you feel unwell, you should consult a doctor in time to avoid delaying the condition.