The only negative side effects I have seen are from creatine "products" and not pure monohydrate. I have taken CM off and on for gosh probably 10 years it seems and have never once had anything negative. I have however tried several creatine "delivery systems" and preworkout formulas that have had undesirable results like cramping, and a serious need to run to the bathroom (You know what I mean!) Most of these formulas are packed with fillers which are completely unnecessary. I've had best results with Creapure. I've also read several articles and the only creatine on the market with any kind of valid research behind it is CM. Most other versions of creatine aren't even proven to work. CM is safe effective and inexpensive. Hard to beat that. I've always taken 5-10 grams daily with grape juice. What is anyone else's preferred method?