Medicine & USMLE


Cardio Drugs - Diuretics
  1. Loop Diuretics
  2. Thiazide Diuretics
  3. Spironolactone
  4. Mannitol


Mannitol is an osmotic diuretic that works to pull water from tissues into the blood, and eventually into the urine. It is used to treat situations of high intracranial pressure or high intraocular pressure. It’s most important side effect is pulmonary edema, so listen closely to the patient’s lung sounds and be sure to report any signs of new crackles to the provider.

Key Points

  • Mannitol
    • Mechanism
      • Osmotic Diuretic
        • A hyperosmolar solution that draws water out of the brain and ECF and excretes it through the urine
        • Increased urine output is expected
    • Clinical Uses
      • Decrease Intracranial Pressure (ICP)
        • Cerebral edema
      • Decrease Intraocular Pressure (IOP)
        • Glaucoma
    • Side Effects and Adverse Reactions
      • Pulmonary edema
        • Can lead to fluid overload in the body
        • Observe for crackles in the lung and report immediately if present
        • Can occur if too much mannitol is given, or if mannitol accumulates in the body due to poor kidney function
        • Contraindicated in patients with CHF
      • Hypokalemia
      • Nausea, vomiting
      • Tachycardia
        • From rapid fluid loss
      • Acidosis