Ramipril + Hydrochlorothiazide is a combination of two medicines: Ramipril and hydrochlorothiazide which lower blood pressure effectively. Ramipril is an angiotensin-converting enzyme (ACE) inhibitor. It works by reducing stress on the heart and relaxing blood vessels so that blood flows more smoothly and the heart can pump blood more efficiently. Hydrochlorothiazide is a diuretic that removes extra water and certain electrolytes from the body. Over time it also relaxes blood vessels and improves blood flow.