Lisinopril is used alone or in combination with other medications to treat high blood pressure in adults and children 6 years of age and older. It is used in combination with other medications to treat heart failure. Lisinopril is also used to improve survival after a heart attack. Lisinopril is in a class of medications called angiotensin-converting enzyme (ACE) inhibitors. It works by decreasing certain chemicals that tighten the blood vessels, so blood flows more smoothly and the heart can pump blood more efficiently.