Diuretics work in the nephron to increase urine output and decrease blood pressure. The major concern with their use is fluid and electrolyte imbalances. Especially concerning is the hypokalemia induced by the medications except for the selective aldosterone blockers (SABs) which are potassium sparing because they work in the distal tubule.

The loop and thiazide/thiazide-like diuretics are used the most frequently. A cross allergy between sulfa and the loop diuretics is possible. Lab effects with the diuretics includes a loss of sodium, chloride, potassium, and magnesium. In patients on digoxin, the induced hypokalemia is especially concerning since hypokalemia potentiates the effects of the drug and toxicity may result.

Spironolactone (Aldactone) is one of the SABs and is a mainstay in the treatment of heart failure. SABs are also used when a patient is diagnosed with diabetes because they will help to protect the kidneys. When patients are taking a SAB, renal function must be closely monitored. If the glomerular filtration rate (GFR) falls the drug(s) must be discontinued. With a decrease in renal function hyperkalemia will result and can be lethal due to effects on the cardiac conduction system.​