[mulle_nat]

No sure about brain harm. But I used creatine for a few months and I got cramps in an intensity like I never experienced before. I then decided it was not worth it for a few watts of cycling FTP increase. So I would not consider it harmless for everbody, but this sideeffect seems pretty rare.

[matwood]

Did you up your water intake along with the creatine? Since you say you're a cyclist you may have just been getting dehydrated.

[terribleperson]

Could it have been dehydration?

[mulle_nat]

I wasn't while cycling, it was when resting or at night sleeping. Could have been dehydration related, but i usually drink a LOT during and afterwards.