Well....considering I was feeling so bad when I started that crappy would have been an improvement, I really can't say I experienced any negative symptoms. I did have constipation initially (wasn't drinking enough water), but that quickly resolved itself and elimination has been pretty much normal for me ever since.
I've never had headaches, mood swings or even bad breath, really. I just feel better all the way around.
Sleep is sounder and more restful. Fatigue, which was terrible before I began, is way better.