I've never had that reaction to either. The worst I ever got was a few years ago. A real burn from IF1...I think I took 5 on an empty stomach....OMG!!!! I learned my lesson there. Since I won't be eating solid on IP I'm going to take the IF1 and 2 at the same time. Or even with superfood. But I never had any sort of body temp change. and I've taken both a lot