StayHappi Isosorbide Mononitrate 20mg Tablet is used to prevent heart-related chest pain (angina). It works by relaxing and widening blood vessels so blood can flow more easily to the heart. This medicine will not treat an angina attack that has already begun. StayHappi Isosorbide Mononitrate 20mg Tablet should be taken empty stomach. Your doctor will decide the dose and how often you should take them. This may change from time to time depending on how well they are working. You should take this medicine as it has been prescribed and keep taking it, even if you feel well. This medicine helps to prevent chest pain in the future. If you stop taking it, your risk of chest pain will increase, especially if you stop taking them suddenly. Lifestyle changes such as diet, exercise, and not smoking may help this medication work better. You can develop tolerance to this medicine over time, which means that the same dose becomes less effective. You have to stick to a really specific dosing schedule to prevent this from happening. The most common side effects include headache, dizziness, changes to your heart rate, and flushing (warmth, redness, or a tingly feeling). If these symptoms bother you or do not go away, your doctor may suggest ways of preventing or reducing them. Some can be reduced by taking painkillers, drinking plenty of fluids, and avoiding alcohol. Before taking this medicine tell your doctor if you have low blood pressure, increased pressure in the eye (glaucoma), kidney disease, or heart failure. Also let your doctor know if you are taking any other medicines as some may affect, or be affected by, this medicine and some may be dangerous to take with it. You should not take any medicine for erectile dysfunction with this medicine. If you are pregnant or breastfeeding, ask your doctor if this medicine is suitable. Your doctor may regularly monitor your blood pressure and heart rate during the treatment with this medicine.