It was basically the 3 minutes it took to activate the second dose. I'll have to try waiting 15-20 minutes sometime. Right now, I think I will take Tom's advice and stay on the lower dose for awhile. I feel best where I am right now, but still, I was really wanting to do the week at full dose 3x/day. It was a bit disappointing, but considering how I felt, I think waiting awhile might be best.