Losartan is a prescription medication used to treat high blood pressure. It is also used to lower the chance of stroke in patients with high blood pressure and to slow the worsening of diabetic kidney disease in patients with type 2 diabetes with a history of high blood pressure. Losartan belongs a group of drugs called angiotensin receptor blockers, which help lower blood pressure by relaxing blood vessels.This medication comes in tablet form and is usually taken once or twice daily. It can be taken with or without food. Common side effects of losartan include stuffy nose, back pain, and dizziness. Do not drive or operate heavy machinery until you know how losartan affects you. Take this medication only as directed. For more information, download the RxWixi mobile app.