If you have high blood pressure, you're far from alone. Roughly one-third of adults in the United States have high blood pressure, according to the Centers for Disease Control and Prevention. Losartan (Cozaar) belongs to a class of drugs called the angiotensin receptor blockers, or ARBs. It is recommended as a first-choice option to treat high blood pressure by the 2014 Joint National Committee guidelines. By blocking angiotensin receptors in the blood vessels and other locations in the body, losartan leads to effects that reduce blood pressure.