The main uses of mannitol include include preventing brain herniation, lowering intraocular pressure, and treating nephrotic syndrome. 1.Dehydration diuretic. Mannitol is an osmotic diuretic, which can treat cerebral edema caused by various reasons, and has the effect of preventing brain hernia. 2.Lowering intraocular pressure. Mannitol dehydration effect, can effectively reduce intraocular pressure. 3.Identifying effect. Through the osmotic diuretic effect of mannitol, it can identify the pre-renal factors and acute renal failure caused by oliguria. 4. Mannitol has adjunctive treatment of nephrotic syndrome and cirrhotic ascites. 5. You can clean the intestine by drinking mannitol before doing colonoscopy and do the preoperative preparation. 6. It can promote the excretion of poisons. After use, it can promote excretion and prevent nephrotoxicity for certain drugs and toxic poisoning. Mannitol adverse reactions include electrolyte disorders, chills, fever, dysuria and so on. It is contraindicated in anuric patients with glomerular necrosis, patients with severe dehydration, patients with active intracranial dehydration, acute pulmonary edema. The drug should be applied under medical supervision.