Last reviewed 2026-04-20 · How we verify

Mannitol

Osmotic diuretic that elevates glomerular filtrate osmolarity to inhibit tubular water reabsorption.

Mannitol is an osmotic diuretic indicated for reducing intracranial pressure, cerebral edema, and elevated intraocular pressure through osmotic gradient mechanisms. It is contraindicated in anuria, severe hypovolemia, pulmonary edema, and active intracranial bleeding except during craniotomy. Significant risks include renal failure with nephrotoxic drugs, electrolyte imbalances affecting cardiac function, and increased lithium toxicity. The drug is rapidly distributed, minimally metabolized, and primarily renally excreted with a short half-life in normal renal function but prolonged elimination in renal impairment.

At a glance

Mechanism of action

Mannitol is a small molecular weight solute confined largely to the extracellular space. When administered intravenously, it elevates the osmolarity of the glomerular filtrate, which hinders tubular reabsorption of water and enhances excretion of sodium and chloride. The increase in extracellular osmolarity induced by mannitol causes movement of intracellular water to the extracellular and vascular spaces, thereby reducing intracranial pressure, cerebral edema, and intraocular pressure.

Approved indications

• Benign intracranial hypertension
• Cerebral edema
• Cystic fibrosis
• Edema
• Hemolysis Prevention
• Ocular hypertension

Common side effects

• Headache
• Inhaled mannitol intolerance as demonstrated by FEV1 decline
• Lightheadedness
• Cough

Drug interactions

• Nephrotoxic drugs (e.g., cyclosporine, aminoglycosides)
• Other diuretics
• Neurotoxic drugs (e.g., aminoglycosides)
• Drugs sensitive to electrolyte imbalances (e.g., digoxin, QT-prolonging drugs, neuromuscular blocking agents)
• Lithium and other renally eliminated agents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.