I drink coffee maybe once every 10 days. I went out for a late lunch and had the iced coffee along with the food. About an hour later I went to the gym and towards the end of my workout I started getting a little lightheaded but I tried to finish my last couple sets. Right after I tried I got very lightheaded and wobbled to the bathroom (lol) and sat down on the couch area they have in there with the TV. I went home about 10 minutes later after waiting for my heart rate to drop back down.