Hydrochlorothiazide (HCTZ) is a thiazide diuretic (commonly known as a "water pill") used to help the body eliminate excess salt and water through urine. It works by inhibiting sodium reabsorption in the distal tubules of the kidneys, leading to decreased fluid retention and lower blood pressure. Widely prescribed for managing hypertension and edema, Hydrochlorothiazide is often combined with other antihypertensive agents to enhance blood pressure control and reduce cardiovascular risk.