what is it for ## I have been on ISOSORB MONO ER 30 MGfor about 3 weeks, some days I get a all day headache, some days I dont. Why the headache? ## This medication, which is a generic for Monoket, is most commonly used to treat angina pectoris. And the headache is a fairly common side effect, it happens to many people that take it and, in some cases, has caused them to have to stop taking it, because they got so severe. It may also cause tiredness and sleep disturbances. You can learn more Isosorbide Mononitrate details here. Are there any other questions? ## I just started taking this drug two days ago my headaches are horrible is there anything I can do for them.......will heat help they told me to take ibuprofen but it does not help much....