Ulcerative colitis causes fatigue and inflammation in the lining of the colon and rectum. Nearly 75 percent of inflammatory bowel disease (IBD) patients – including those with ulcerative colitis – experience fatigue during a flare-up.
A 2011 study also revealed that nearly 30 percent of participants had fatigue even when not experiencing a flare-up.
It can get so bad that it may actually impair one's ability to carry out daily functions.