Only once, last year. I was getting multiple vaccination shots ahead of my trip to Thailand and normally they were supposed to be spaced out, but because of the timeframes involved I couldn't have that luxury. I don't have any problem with injections, never really have since I was a teen, so when I got light headed I didn't know what was going on. I nearly fainted, but the doc caught me before I slumped over in my chair and told me to get on the bed and lie down for a bit. I honestly don't know if I completely fainted or not, though, because I pretty much remember the whole thing.