Lisinopril/hydrochlorothiazide is a combination medication used to treat high blood pressure (hypertension). It combines lisinopril, an angiotensin-converting enzyme (ACE) inhibitor, with hydrochlorothiazide, a diuretic. Lisinopril helps lower blood pressure by relaxing and widening blood vessels, making it easier for blood to flow. Hydrochlorothiazide reduces blood pressure by helping the kidneys remove excess fluid and salt from the body. Together, these medications effectively lower blood pressure, decreasing the risk of stroke, heart attack, and kidney problems associated with hypertension.