Angina, GTN and a Humongous Headache

Had chest tightness the other night, have been getting more of these in recent times so used my GTN spray as I usually do. Normally don't have any problems with it, maybe get a bit light headed but that's about it. But that night got a humongus headache after using the spray, head was pulsating and felt like it was going to explode. First time ever in all the years I have been using my GTN. Went away after about 15 mins. I wonder if others get this sort of thing from time to time?

Should add I also take Isosorbide Mononitrate SR 60mg daily in the morning and only use the GTN spray, as instructed by my cardiologist, when the angina symptoms etc. crop up which has been more frequent over the past two years than when I was first given the spray a number of years ago.

As to why I have been having an increase in angina episodes, see my previous post "A Salutary Lesson" and the discovery of a new 99% blockage in my right coronary artery.

Information on using GTN spray can be found here: http://www.nps.org.au/medicines/heart-blood-and-blood-vessels/angina-medicines/glyceryl-trinitrate-angina-medicines/nitrolingual-pumpspray-sublingual-spray