Angiotensin-Converting Enzyme Inhibitors (ACE inhibitors) are a class of medications primarily used to treat high blood pressure and heart failure. They work by blocking the action of the enzyme that converts angiotensin I to angiotensin II, a substance that narrows blood vessels. By inhibiting this process, ACE inhibitors help relax blood vessels, making it easier for the heart to pump blood and lowering blood pressure. Common examples of ACE inhibitors include lisinopril, enalapril, and ramipril. These medications can also provide kidney protection, especially in patients with diabetes. While generally well-tolerated, they may cause side effects such as a persistent cough or elevated potassium levels.