Anemia, meaning a low level of iron in the blood, can occur in patients with ulcerative colitis. People with anemia can experience symptoms like fatigue, dizziness, shortness of breath, and heart palpitations. An iron deficiency in the body means that your blood cells aren’t carrying enough oxygen around the body. In severe cases, anemia can be deadly. If you suffer from ulcerative colitis, you may have internal bleeding as well as blood loss in the rectum, causing iron levels to deplete. This can cause weakness as well as confusion and loss of concentration.