HCTZ is a pottasium wastinf diuretic. The usual starting prescribed dose is 25 mg a day. Usually no side effects; but low blood potassium should be watched for. HCTz is weaker than lasix and also less likely to cause severe hypokalemia. HCTZ mixed with triamterene, which is a potassium sparing diuretic usually decreases the risk of potsssium abnormalitites in people with normal kedney function. Periodic potassium level measurement is prudent for with any diuretic use, however...