Mannitol is an osmotic laxative and can be used for laxative purposes. Mannitol belongs to the osmotic laxative, which can promote the peristalsis of the gastrointestinal tract, thus providing a laxative effect. Mannitol can also be used as a dehydrating agent for the treatment of cerebral edema, lowering intracranial pressure and preventing cerebral herniation, etc. It can also lower intraocular pressure and be used in the preparation of intraocular surgery. For patients who have been diagnosed with acute tubular necrosis, severe water loss, active intracranial hemorrhage, etc., try to avoid the use of mannitol as much as possible, so as not to cause discomfort. In addition, patients with constipation, it is recommended not to take oral mannitol for a long time, so as not to cause drug dependence, or aggravate constipation, etc. You can drink more water, eat more fresh vegetables and fruits to promote intestinal peristalsis and relieve constipation. Repeated constipation should be timely hospital diagnosis and treatment, clear causes of constipation, targeted treatment, drugs should be taken under the guidance of a doctor.