Originally posted by Cilian McHugh
This link has a pretty straightfoward rundown of the available research on Creatine and other supplements.
I also found an article in a back issue of Muscular Development where they asked four or five respected Strength & Conditioning Researchers and Coaches (forget the majority of the names right now but William Kraemer was one of them) a load of questions about Creatine, there experience using it with their athletes and their interpretation of the available research. It's a good read and I will give it to you next time I see you, but in the meantime essentially what they said was that in their experience they had not seen any serious side-effects and that it had enhanced athletic performance at all levels (including in Muscular Dystrophy patients (not athletic I know, but interesting nonetheless), who were able to tolerate much higher dosages before meeting diminishing returns). They also said that large doses were harmful and pointless and greater education was needed as to recommended dosages, as the typical 'if some is good then more is better' mentality seemed to be all to prevailing among young athletes.
All agreed that long-term research in the area was severely lacking. (Although that was written nearly five years ago, so perhaps there are some floating around now).
Another interesting consensus was that they had never seen the adverse side-effects commonly associated with Creatine usage recreated in laboratory conditions. A possible explanation offered for the anecdotal evidence of bloating and muscular cramps, was poor hydration practices while training in conjunction with the muscles' increased ability to retain water.