For the effect of mannitol, it is mainly used for dehydration. Clinically, it is mainly used for the treatment of cerebral edema caused by various reasons, effectively reducing intracranial pressure and preventing the occurrence of brain herniation, then it can reduce intraocular pressure and be used for the preoperative preparation of glaucoma, as well as for the prevention of acute tubular necrosis, then for some trauma-induced limb swelling, spinal edema, spinal cord injury, you can also use mannitol for dehydration, the effect is also very good.