Overview: Losartan is used for high blood pressure or in certain people with high blood pressure or diabetes. Common side effects may include dizziness, stuffy nose, or back pain. Do not drive or. Losartan, sold under the brand name Cozaar among others, is a medication used to treat high blood pressure (hypertension). [4] It is in the angiotensin receptor blocker (ARB) family of medication, and is considered protective of the kidneys. Losartan is a prescription drug to treat high blood pressure, diabetic nephropathy, and stroke risk. Learn about side effects, warnings, dosage, and more. Losartan is used to treat high blood pressure and to help protect the kidneys from damage due to diabetes. Learn about side effects, drug interactions, dosages, warnings, and more. Losartan is in a class of medications called angiotensin II receptor antagonists. It works by blocking the action of certain natural substances that tighten the blood vessels, allowing the blood to flow more smoothly and the heart to pump more efficiently. Losartan is an angiotensin II receptor blocker (ARB) that relaxes blood vessels, lowers blood pressure, and reduces proteinuria (protein in urine). In patients with type 2 diabetes and hypertension, it significantly slows the progression of diabetic nephropathy. Losartan is used to treat high blood pressure (hypertension). It is also used to lower the risk of stroke in certain people with heart disease. Losartan is a safe, effective and widely prescribed blood pressure medication that offers real benefits for heart health. While it does come with one key potential side effect—elevated potassium levels—this can actually work in your favor depending on your individual health needs. Losartan is an angiotensin II receptor blocker (ARB). It works by blocking a substance in the body that causes blood vessels to tighten. As a result, losartan relaxes the blood vessels. A lower blood pressure will increase the supply of the blood and oxygen to the heart. Losartan (Cozaar) is an angiotensin II receptor blocker (ARB) commonly prescribed to treat high blood pressure. Common losartan side effects include dizziness, respiratory infections, and back or joint pain. Fatigue, headache, and digestive issues are also possible.