Furosemide is a loop diuretic that acts by inhibiting the reabsorption of sodium and chloride (via the Na/K/2Cl cotransporter) in the thick ascending limb of the loop of Henle. It enhances the excretion of sodium, potassium, calcium, chloride, and water. Furosemide is used frequently in the intensive care unit (ICU) setting for diuresis.

Intravenous furosemide begins to work in 5 minutes, peaks at 30 minutes, and lasts for about 2 hours. The elimination half-life is approximately 30 to 120 minutes. A dosing interval of 6 hours allows for four to five half-lives of elimination. Typically, with the appropriate dose of IV furosemide, a maximal response will be seen within the first hour and the increased urine output will continue in a tapering fashion for up to 6 hours. A large initial response followed by a rapid tapering of urine output may be an indication that the patient is not quite ready for diuresis.