Hydrochlorothiazide, sold under the brand name Hydrodiuril among others, is a diuretic medication used to treat hypertension and swelling due to fluid build-up. Other uses include treating diabetes insipidus and renal tubular acidosis and to decrease the risk of kidney stones in hypercalciuria. Hydrochlorothiazide is taken by mouth and may be combined with other blood pressure medications as a single pill to increase effectiveness. Hydrochlorothiazide is a thiazide medication which inhibits reabsorption of sodium and chloride ions from the distal convoluted tubules of the kidneys, causing a natriuresis. This initially increases urine volume and lowers blood volume. It is believed to reduce peripheral vascular resistance.
Potential side effects include poor kidney function, electrolyte imbalances, including low blood potassium, and, less commonly, low blood sodium, gout, high blood sugar, and feeling lightheaded with standing.