Adverse reactions of mannitol tablets include water-electrolyte disorders, allergy, chills, fever, etc. It is contraindicated in people with water loss, and in people with active intracranial hemorrhage. 1.Adverse reactions: water electrolyte disorders, allergy, chills, fever, etc.. Hydroelectrolyte disorders: mannitol has diuretic effect, if excessive diuresis will lead to decreased blood volume, aggravating the symptoms of oliguria. Allergic reactions: such as rash, anaphylaxis, urticaria, dyspnea. There are also chills, fever, thrombophlebitis. 2. Contraindications: Mannitol tablets are prohibited in patients with severe water loss, those with active intracranial hemorrhage, patients with acute pulmonary edema, and those who have been diagnosed with renal tubular necrosis. If you need to take mannitol tablets, it is recommended to consult a professional physician and standardize the use of medication under their guidance.