I've used it doc and I prefer it over clen. For me the sides are barely noticeable, much less if any shakes, muscle cramping, and headaches. I also felt it was just as effective as a fat burner too. Could've been the fact I wasn't dogged by the constant harsh sides from the clen and was able to perform in the gym more efficiently too. But even if it's only slightly less effective at burning fat it's worth it to me.