Will taking creatine monohydrate adversely affect my ulcertaive colitis? (e.g., cause flares, etc.)

Creatine and colitis: Creatine monohydrate is usually safe in ulcerative colitis at the maintenance dose. Please consider not doing the loading dosing as this is sometimes tough on normal intestines.

Not during flares.: Since intestinal cramping and diarrhea can both be side effects of creatine supplements, I would recommend that avoiding them might be your best bet, especially during a UC flare, as it might confuse things. If you are in remission in between flares, a small amount of creatine may be okay. However, most people do not benefit from creatinine supplements anyway, even if they are weightlifting.