This is likely a complete coincidence, so take my experience with a grain of salt. However… I am somewhat convinced that creatine caused me to develop appendicitis last summer about 5 days into a supplementation cycle. My best guess is that increased fluid retention (caused by creatine) caused vascular congestion at the verniform appendix.

On the (monkey’s paw) plus side, the perioperative IV fluids plumped up my muscles and gave a muscle man appearance that I was after for several days. I believe I was up 10-15 lbs in water weight when I came home.