If a patient becomes dehydrated, he should not take oral medication at this time, but should establish intravenous access and treat dehydration by intravenous infusion, which is divided into mild dehydration, moderate dehydration and severe dehydration. Mild dehydration can be treated by giving appropriate glucose water or isotonic saline, such as 0.9% saline and 5% glucose injection, according to the kilogram of body weight. If rehydration is not possible in mild dehydration, you can also take 5% glucose injection or drink 0.9% saline or sodium chloride injection, but oral administration is much less effective than intravenous rehydration. In case of moderate dehydration and severe dehydration, oral medication cannot relieve the symptoms of dehydration, so rehydration must be given, and isotonic fluids should be chosen to replenish the lost ions according to ion analysis and blood gas analysis.