How the dose is calculated
Mannitol for raised intracranial pressure is dosed in g/kg, typically 0.25-1 g/kg per dose, using a 20% solution (200 mg/mL).
Typical dosing range
| Dose | When used |
|---|---|
| 0.25 g/kg | Lower end, repeated dosing, or renal/cardiac caution |
| 0.5 g/kg | Standard starting dose for raised ICP |
| 1 g/kg | Higher/loading dose for acute severe elevation in ICP |
Repeat dosing is guided by serum osmolality (generally keeping it below ~320 mOsm/kg) and clinical/ICP response — mannitol is an osmotic diuretic, so monitor volume status, electrolytes, and renal function with repeated doses.
Clinical use
- Used for acute management of raised intracranial pressure (traumatic brain injury, mass lesion, some cases of stroke) as a bridge to definitive treatment.
- Works by osmotically drawing fluid out of brain tissue and across the blood-brain barrier, reducing intracranial volume and pressure within minutes.
- Causes an osmotic diuresis — ensure adequate hydration and monitor for hypovolaemia and electrolyte disturbance with repeated dosing.
Frequently asked questions
What is mannitol used for?
Acute reduction of raised intracranial pressure, most commonly in traumatic brain injury or a mass lesion, by osmotically drawing fluid out of the brain.
How often can mannitol doses be repeated?
Repeat dosing is guided by clinical response and serum osmolality (generally kept below roughly 320 mOsm/kg) rather than a fixed interval — check local protocol and involve neurosurgery/critical care.
What should be monitored during mannitol therapy?
Volume status, serum electrolytes, renal function, and serum osmolality — mannitol causes a significant osmotic diuresis that can lead to hypovolaemia and electrolyte disturbance with repeated doses.
References
- Carney N, et al. Guidelines for the Management of Severe Traumatic Brain Injury, 4th Edition. Neurosurgery. 2017;80:6-15.