Hydrochlorothiazide is a diuretic medication commonly used to treat high blood pressure and edema (fluid retention) associated with conditions such as heart failure or kidney disorders. It works by inhibiting sodium reabsorption in the kidneys, leading to increased urine output and reduced fluid buildup. This helps lower blood pressure and alleviate swelling. Hydrochlorothiazide is often prescribed as part of a comprehensive treatment plan that may include lifestyle changes and other medications.