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Osmotic Diuretic / ICP reduction Pregnancy: Use only if essential for life-threatening raised ICP.

Mannitol 20%

Brand names: Mannitol 20% Infusion

Adult dose

Dose: 0.25–1 g/kg IV over 15–30 minutes
Route: IV infusion via filter (crystallisation may occur)
Frequency: Every 6 hours as needed (avoid prolonged use)
Max: 2 g/kg/dose; cumulative daily max guided by osmolality
Raised ICP / herniation: 0.25–1 g/kg IV over 20 min. Repeat doses guided by clinical response and serum osmolality (target <320 mOsm/kg). Use 200 mg/mL (20%) solution. Requires warming if crystallised.

Paediatric dose

Dose: 0.5 g/kg
Route: IV
Frequency: Every 6 hours as needed
Max: 1 g/kg/dose
Concentration: 0.2 g/ml
0.25–1 g/kg IV over 15–30 minutes. Same principles as adult dosing — guided by ICP monitoring and serum osmolality.

Dose adjustments

Renal

Use with extreme caution in renal failure — risk of acute tubular necrosis and pulmonary oedema.

Hepatic

No specific adjustment; monitor fluid balance closely.

Paediatric weight-based calculator

0.25–1 g/kg IV over 15–30 minutes. Same principles as adult dosing — guided by ICP monitoring and serum osmolality.

Clinical pearls

  • Use in-line filter — may crystallise at low temperatures (warm to dissolve)
  • Monitor serum osmolality: stop if >320 mOsm/kg (risk of renal failure)
  • Foley catheter essential — expect large volume diuresis
  • Hypertonic saline (3%) is an alternative especially in hypovolaemia
  • Repeat doses become less effective — osmotic equilibration (rebound)

Contraindications

  • Anuria
  • Severe renal impairment
  • Intracranial bleeding (active)
  • Severe dehydration
  • Pulmonary oedema
  • Hyponatraemia

Side effects

  • Electrolyte disturbances (hyponatraemia, hypokalaemia)
  • Fluid overload (initial expansion before diuresis)
  • Renal failure (excessive or prolonged use)
  • Rebound ICP rise
  • Thrombophlebitis at infusion site

Interactions

  • Digoxin — electrolyte disturbances increase toxicity risk
  • Ciclosporin — reduced levels
  • Lithium — increased excretion (reduced levels)

Monitoring

  • Serum osmolality (keep <320 mOsm/kg)
  • U&E
  • Urine output
  • ICP (if monitored)
  • Fluid balance

Reference: BNFc; BNF; UK ICU guidelines; NICE NG234 TBI. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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