The main treatment for hypotension caused by dehydration is to replenish adequate amounts of fluids, but the ionic status of the patient should be clarified when replenishing the amount of fluids. If the patient sweats more because of the summer heat or has more watery stools due to gastrointestinal discomfort, more sodium is often excreted in addition to water. For patients with hyponatremia, it is important to supplement sodium chloride along with water. If only water is supplemented, it will aggravate the hyponatremia and further lead to the occurrence of acute cerebral edema, which has certain risks. In addition, for patients with chronic cardiac insufficiency, attention should be paid to the speed of rehydration while supplementing water, and try to take it orally and avoid intravenous infusion, as rapid rehydration may increase the burden on the heart to induce heart failure.