Rehydration salts are mainly made by mixing 3.5 grams of sodium chloride, 2.5 grams of sodium bicarbonate, 1.5 grams of potassium chloride, and 22 grams of anhydrous dextrose, and then diluting them with 1 liter of water. The most important ions for maintaining osmotic pressure in the body are sodium and potassium ions, and the stability of osmotic pressure is necessary to maintain life. Therefore, when the body is mildly to moderately dehydrated due to acute diarrhea or profuse sweating, an osmotic pressure abnormality occurs, and then it is necessary to supplement oral rehydration salts that are rich in sodium and potassium. When replenishing fluids for infants and young children, the principle of multiple replenishments and a small amount at a time should be strictly followed, and the replenished mixed solution should be prepared on the same day and not used every other day. If the organism develops symptoms such as dry mouth, decreased urine output, dizziness, etc., medical attention should be sought immediately.