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 a commonly prescribed blood pressure medication. While well tolerated, losartan can cause side effects. Here’s what you need to know. Find patient medical information for Losartan (Cozaar, Arbli) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings The bottom line on losartan side effects 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, 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 also used to decrease the risk of stroke in patients with high blood pressure and enlargement of the heart. It is also used to treat kidney problems in patients with type 2 diabetes and a history of hypertension. This medicine is available only with your doctor's prescription. Learn about the side effects of losartan, from common to rare, for consumers and healthcare professionals. Cozaar (Losartan): Protecting Kidneys in Diabetes Updated: September 2025 * Category: Antihypertensive / Renal Protection How Cozaar Works 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. 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 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.