Losartan (loe SAR tan; hye droe klor oh THYE a zide) treats high blood pressure. It may also be used to prevent a stroke in people with heart disease and high blood pressure. It relaxes your blood vessels and helps your kidneys remove more fluid through the urine, which lowers blood pressure. This medication is a combination of an ARB and diuretic. This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.