Losartan is an angiotensin II receptor blocker (ARB) that helps relax blood vessels, reducing blood pressure and improving blood flow. It is commonly prescribed to treat high blood pressure (hypertension), protect kidney function in type 2 diabetic patients with proteinuria, and reduce the risk of stroke in patients with high blood pressure and left ventricular hypertrophy. The usual starting dose is 25 mg once daily, with a maximum recommended dose of 100 mg per day, depending on the patient's condition and response to treatment. Losartan is generally well-tolerated, but potential side effects include dizziness, fatigue, and elevated potassium levels. It should be used with caution in patients with liver or kidney issues and is not recommended during pregnancy, especially in the second and third trimesters. Regular monitoring of blood pressure and kidney function is advised during treatment.