Which medication is used to decrease intracranial pressure in a head injury patient?

• A. Diphenhydramine
• B. Morphine
• C. Furosemide
• D. Mannitol

Answer: (D)

Lowering intracranial pressure after head injury relies on creating an osmotic pull that withdraws water from swollen brain tissue. Mannitol does this effectively: when given IV, it raises plasma osmolality, drawing water out of the cerebral edema into the bloodstream, which reduces brain volume and thus lowers intracranial pressure. This helps protect cerebral perfusion by keeping pressure from overwhelming blood flow to the brain.

Use is typically as a bolus dose with careful monitoring of urine output, blood pressure, electrolytes, and kidney function. Be mindful of contraindications and risks: it’s not used in anuric kidney failure or when there is significant dehydration or severe heart failure/pulmonary edema, and rebound increases in ICP can occur if therapy is stopped abruptly. Hypertonic saline is an alternative osmotic therapy.