I almost opt out and have alarmed the nitro machine few times already. I do not use any medication that can cause that and never have anything in my possession that can be even remotely considered dangerous. My "false positives" have always been cleared by an RPD. I think though it's only the question when the RPD will set an alarm and I will not be cleared. What are my option at that point?
I fly for business and I can't really afford to just walk away. There will be a lot of money lost for me then.