Aldactazide is a medicine used in the treatment of conditions such as edema and hypertension. Edema is the collection of fluid inside the body, and may result as a symptom of conditions such as congestive heart failure, nephritic syndrome and cirrhosis. Aldactazide is composed of two different drugs: spironolactone and hydrochlorothiazide. Both are diuretics in the sense that they prevent the accumulation of fluid in the body by eliminating salt. Spironolactone is different, though, as it prevents the loss of potassium.