###Human: Is my headache a side effect of any medicine? ###Assistant: Hi. I have gone through your query in detail. There are certain things that would need more clarity for a complete diagnosis. First, it is strange that you have a blockage at such young age. I would suggest that you should get yourself revaluated for CAD (coronary artery disease). The possible reason for the headache is your medicine Monit SR (Isosorbide mononitrate) can be a cause of headache. Nitrate headaches are well known and we would need to see if this is the reason in your case. Also, since you have CAD at such a young age, there can be a possibility of carotid artery blockage which might be giving you a headache. Get that evaluated. Revert back with the reports to a cardiologist online -->