What are the effects of mannitol?
Nov 05, 2025
Source: Cainiu Health
Dr. Yang Ziqi
Introduction
In general, mannitol, a commonly used osmotic agent in clinical practice, has several main effects including dehydration and reduction of intracranial pressure, diuresis, prevention of acute kidney injury, assistance in lowering intraocular pressure, and promotion of drug excretion. When using mannitol, the dosage and infusion rate must be strictly controlled according to medical instructions, and the patient's renal function, electrolyte levels, and urine output should be closely monitored.
Generally, mannitol is a commonly used osmotic agent in clinical practice, with main effects including dehydration and reduction of intracranial pressure, diuresis, prevention of acute kidney injury, assistance in lowering intraocular pressure, and promotion of drug excretion. A detailed analysis is as follows:
1. Dehydration and reduction of intracranial pressure: After intravenous infusion, mannitol increases plasma osmotic pressure, promoting the shift of fluid from brain tissue into blood vessels, which is then excreted via the kidneys. This helps reduce cerebral edema and lower intracranial pressure. This effect is commonly used to treat elevated intracranial pressure caused by conditions such as cerebral hemorrhage, cerebral infarction, and intracranial tumors, thereby relieving symptoms like headache, vomiting, and impaired consciousness.
2. Diuresis: Once in the body, most of the mannitol is not reabsorbed by renal tubules. It creates a hypertonic environment in the renal tubules, inhibiting water reabsorption and increasing the excretion of electrolytes such as sodium and potassium, thus producing a significant diuretic effect. Clinically, it is often used to treat oliguria in early acute renal failure or to assist in removing excess fluid from the body and improving edematous conditions.
3. Prevention of acute kidney injury: Following certain surgeries or severe trauma, intravenous infusion of mannitol can increase renal blood flow and glomerular filtration rate, reduce ischemic damage to renal tubules, and flush the tubules through diuresis, preventing tubular obstruction. This helps lower the risk of developing acute kidney injury.
4. Assistance in lowering intraocular pressure: The hyperosmotic action of mannitol promotes the transfer of fluid from ocular tissues into the bloodstream, reducing the volume of intraocular fluid and thereby decreasing intraocular pressure. This effect can be used short-term during acute attacks of glaucoma to rapidly relieve high pressure on the optic nerve, buying time for further treatment.
5. Promotion of drug excretion: In patients with certain drug intoxications, mannitol infusion can increase urine output, accelerating the elimination of toxic drugs and their metabolites from the body, reducing drug-induced toxicity and aiding in the management of poisoning.
When using mannitol, it is essential to strictly follow medical instructions regarding dosage and infusion rate, closely monitor changes in renal function, electrolyte levels, and urine output, and avoid adverse reactions such as electrolyte disturbances and renal impairment due to improper use, ensuring safe and effective medication administration.
