| Watery diarrhea |
| Osmotic diarrhea |
| Carbohydrate malabsorption |
| Osmotic laxatives (eg, Mg++, PO4–3, SO4–2) |
| Secretory diarrhea |
| Bacterial toxins |
| Bile acid malabsorption |
| IBD (some cases) |
| Crohn disease |
| Microscopic colitis |
| Collagenous colitis |
| Lymphocytic colitis |
| Medications and toxins |
| Disordered motility |
| Diabetic autonomic neuropathy |
| IBS |
| Postsympathectomy diarrhea |
| Postvagotomy diarrhea |
| Endocrinopathies |
| Addison's disease |
| Neuroendocrine tumors |
| Hyperthyroidism |
| Mastocytosis |
| Medullary carcinoma of the thyroid |
| Idiopathic secretory diarrhea (epidemic and sporadic) |
| Stimulant laxative abuse |
| Neoplasia |
| Colon carcinoma |
| Lymphoma |
| Villous adenoma |
| Vasculitis |
| Inflammatory diarrhea |
| Diverticulitis |
| Infectious diseases |
| Invasive bacterial infections (eg, tuberculosis, yersinosis) |
| Invasive parasitic infections (eg, amebiasis, strongyloidiasis) |
| Pseudomembranous colitis |
| Ulcerating viral infections (eg, cytomegalovirus, herpes simplex virus) |
| IBD (most cases) |
| Crohn disease |
| Ulcerative colitis |
| Ulcerative jejunoileitis |
| Microscopic colitis (some cases) |
| Ischemic colitis |
| Neoplasia |
| Colon cancer |
| Lymphoma |
| Radiation colitis |
| Fatty diarrhea |
| Malabsorption syndromes |
| Mesenteric ischemia |
| Mucosal diseases (eg, Crohn disease, Whipple's disease) |
| SBS |
| SIBO |
| Maldigestion |
| Inadequate luminal bile acid concentration |
| Pancreatic exocrine insufficiency |
