A vasodilator is a type of medication or substance that helps widen blood vessels. By relaxing the smooth muscles in the walls of blood vessels, vasodilators increase blood flow and lower blood pressure. They are often used to treat conditions like hypertension and heart failure. Common examples of vasodilators include nitroglycerin and hydralazine. These medications can help improve oxygen delivery to the heart and other organs, making them essential in managing cardiovascular diseases. However, they may also cause side effects such as headaches or dizziness due to the sudden drop in blood pressure.