Isosorbide mononitrate 30 mg is used to prevent chest pain (angina) caused by coronary artery disease (heart disease) . It belongs to a group of medicines called nitrates, which work by relaxing the blood vessels and increasing the supply of blood and oxygen to the heart while reducing its workload. When used regularly on a long-term basis, it helps prevent angina attacks from occurring. It is important to note that isosorbide mononitrate does not work fast enough to relieve the pain of an angina attack that has already started. This medicine is available only with a doctors prescription and is usually taken orally in the form of tablets or capsules.