I've never had a problem with it until one day when we were certifying. I had been up all night on a mission and hadn't eaten anything that morning. The guy stabbing me wasn't very good and went all the way through the vein. I stood up after he removed the needle and said, "now it's my turn." The next thing I remember is waking up on the ground with everyone standing around me going, "Are you alright?" It was quite embarrassing.