The baby fever is usually to sweat to reduce fever, after eating antipyretic drugs also need to sweat, if in a dehydrated state antipyretic drugs are less effective, so the fever whether before taking antipyretic drugs, or after eating antipyretic drugs should be supplemented with water. Fever is also accompanied by electrolyte loss, the best way to quickly rehydrate is to drink hypotonic oral rehydration salts, not only to replenish water but also to replenish electrolytes, and hypotonic oral rehydration salts in patients with fever compared to drinking plain water, warm water rehydration is faster, more direct, and more easily digested to the intestinal tract absorption. If the vomiting is particularly obvious, medication, water can not drink into the intravenous rehydration, intravenous rehydration is very direct, can solve the problem quickly, but in the intravenous rehydration still need to maintain rehydration, usually can be oral hypotonic oral rehydration salts.