If there are symptoms, the following may indicate colon cancer: 1  Abdominal pain and tenderness in the lower abdomen. 2  Blood in the stool. 3  Diarrhea, constipation, or other change in bowel habits. 4  Narrow stools. 5  Weight loss with no known reason.
Diarrhea may be caused by: lactose intolerance. bacterial infection. damage to intestinal wall. hormone-producing tumors (including certain types of pancreatic neuroendocrine tumors) inflammation or ulceration of the bowel. malabsorption caused by surgery that has shortened the intestines. pancreatic enzyme insufficiency.
Without the good bacteria, other microbes can grow out of control and irritate the gut causing diarrhea. Additional medicines that can cause diarrhea include: blood pressure medications, cancer drugs, antacids containing magnesium, NSAIDS, and antiarrhythmia heart medicines. Parasites.