Mannitol is a dehydrating drug, which can rapidly increase plasma osmolarity after intravenous injection, resulting in tissue dehydration by transferring interstitial fluid to plasma. Mannitol is not easily reabsorbed when it passes through the kidneys, resulting in reduced water reabsorption and increased renal drainage, producing an osmotic diuretic effect. Mannitol can rapidly increase plasma osmolarity after intravenous injection, producing tissue dehydration and osmotic diuretic effects, reducing intracranial pressure and intraocular pressure, and preventing acute kidney injury. Mannitol can treat the following diseases, used to treat cerebral edema, edema caused by large burns, refractory edema with hyponatremia, also treat glaucoma, prevent and treat acute renal failure and dehydration. mannitol has other uses: 1. preoperative intestinal preparation. 2. biliary ascariasis. 3. refractory hyperthermia. 4. severe pulmonary heart disease, right heart failure. 5. to remove blood accumulation in the intestine and prevent liver Coma. 6, Used as a flushing agent in transurethral resection of the prostate. 7, Used as an auxiliary diuretic measure in the treatment of nephrotic syndrome, cirrhotic ascites, especially when accompanied by hypoproteinemia. 8, Can be used for certain drugs overdose or poisoning, such as barbiturates, lithium, salicylates and bromides. This drug can promote the excretion of the above substances and prevent the occurrence of nephrotoxicity, the need to test the indicators of renal function before use. Adjust the dosage according to the renal function, and use with caution in patients with severe renal failure.