I attended a very interesting talk from a pharmacist at my local hospital two years ago, during which we discussed the use of GTN.
This is typically a spray that you squirt under your tongue when you have chest pain from angina. It's also available in other forms.
The pharmacist warned about headaches being a side effect and it would be easy to deduce that she considered the spray to be only used when you're in distress.
Actually, I've never had a headache from using it - except when traces of it were found on routine swabbing of my iPad at an airport - this caused quite a headache!
I had suffered for a whole year when I didn't use the spray because of dire warnings. Being able to use the spray, when needed, enabled me to live a more normal life.
In my opinion, patients should take their first dose accompanied by a GP or nurse to help overcome this fear.
The pharmacist didn't seem to know that NHS advice encourages patients to use the spray as a precaution when you know you have to do something that will, based on experience, induce angina.
In her opinion, you shouldn't use it more than twice a week.
I'm sorry, but this advice is contradicted by NHS advice all over the web.
If the pharmacist is wrong, I shudder to think of how many people are suffering angina pain rather than use the spray which was prescribed for them. And, if she's right, well the webmasters of the NHS better get to work on their sites....