Major Uses

Mannitol is a hexahydric alcohol that functions as an osmotic diuretic and is used to treat glaucoma, head trauma, and other causes of edema in dogs, cats, and horses. Although this drug is not approved by the Food and Drug Administration for use in animals, it is prescribed legally as an extra-label drug by veterinarians.

Mannitol works by drawing fluid from the intracellular space to cause cellular dehydration and reduce swelling. Use of this drug reduces intraocular pressure, intracranial pressure, blood viscosity, and brain size. It also causes reflex cerebral vasoconstriction.

Common Precautions

Side effects associated with proper use of mannitol are minimal. Fluid and electrolyte imbalances are possible.

Mannitol is not safe for use in pregnant animals. It should not be used in animals suffering from urinary tract obstruction, congestive heart failure, or anuric renal failure. The drug is not safe for use in severely dehydrated animals or in those suspected of pulmonary congestion, pulmonary edema, or intracranial hemorrhage.

Animals undergoing treatment with mannitol must continue to produce urine. Urine flow typically increases within 15 minutes of starting intravenous infusion with the drug. If this increase does not occur, treatment may be stopped.

It is important to determine electrolyte status before and after treatment with mannitol. Blood chemistry tests should be ordered before and after IV infusion.

Mannitol may interact with certain antibiotics or other medications.

Mannitol should not be used in animals with a known allergy or hypersensitivity to the drug. Symptoms of overdose may include a decrease in urine output, breathing difficulties, and seizures. Any known or suspected overdose should be reported to a veterinarian right away.


Mannitol should be stored at room temperature, away from light, and out of the reach of children and animals. It should not be exposed to extreme temperatures or kept in the refrigerator. Chilling may cause the solution to form crystals. These may be dissolved with warming and agitation.


Mannitol is available as an injectable solution in concentrations of 5%, 10%, 15%, 18%, 20%, and 25%.

Dosing depends on the condition being treated. To treat oliguric renal failure, the typical dose is 0.125 to 0.25 g/lb (0.25 to 0.5 g/kg) intravenously over 15 to 20 minutes, with the dose being repeated every 4 to 6 hours, as necessary. To reduce intracranial pressure, the typical dose is 0.75 g/lb (1.5 g/kg) of a 15% to 25% solution given intravenously over 30 to 60 minutes. To reduce intraocular pressure, the typical dose is 0.5 to 1.5 g/lb (1 to 3 g/kg) of a 15 % to 20% solution intravenously over 30 minutes, with the dose being repeated every 12 hours for 2 days, if necessary.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of mannitol is missed, a veterinarian should be consulted for advice. Two doses of this medication should not be given at the same time.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.