Digestive Health Understanding Functional Diarrhea By Barbara Bolen, PhD twitter Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome. Learn about our editorial process Barbara Bolen, PhD Medically reviewed by Medically reviewed by Robert Burakoff, MD, MPH on December 15, 2020 linkedin Robert Burakoff, MD, MPH, is board-certified in gastroentrology. He is the vice chair for ambulatory services for the department of medicine at Weill Cornell Medical College in New York, where he is also a professor. He was the founding editor and co-editor in chief of Inflammatory Bowel Diseases. Learn about our Medical Review Board Robert Burakoff, MD, MPH on December 15, 2020 Print Functional diarrhea is a health condition in which a person experiences chronic diarrhea without any clear-cut cause. It is one of the functional gastrointestinal disorders (FGD), which are defined as recurrent digestive system problems without any accompanying signs of a disease, injury, or structural problem identified on diagnostic testing. A lack of abnormalities on diagnostic tests does not mean that functional diarrhea and FGD are not valid, real, or important. The symptoms are real and can cause negative health effects, and you may benefit from lifestyle modifications or medical treatment. Dan Dalton/Caiaimage/Getty Images Criteria The Rome IV diagnostic criteria categorize FGD, including functional diarrhea, according to specific definitions. Functional diarrhea criteria are: The experience of loose or watery stools Lack of pain with the diarrhea Diarrhea occurring in at least 75% of bowel movements At least six months of symptoms, at least three months of which must be consecutive No identifiable cause (structural or biochemical) Functional Diarrhea and Irritable Bowel Syndrome Irritable bowel syndrome (IBS) is a type of FGD. When chronic diarrhea is the predominant symptom of IBS, diarrhea-predominant irritable bowel syndrome (IBS-D) may be diagnosed. Functional diarrhea is characterized by a lack of abdominal pain, while IBS-D can cause abdominal pain. Both disorders involve frequent loose stools and may also involve such symptoms as urgency, gas, bloating, mucus in the stool, and feelings of incomplete evacuation. Functional diarrhea is often considered a subtype of IBS-D. Diagnosis Functional diarrhea is diagnosed through a process of exclusion. This means that you can be diagnosed with functional diarrhea only after other digestive disorders or health problems have been ruled out. Typically, your doctor will take your health history, do a physical examination, and may order diagnostic lab tests, such as blood work and a stool sample analysis. Other possible tests can include imaging examinations, such as abdominal computed tomography (CT), ultrasound, or magnetic resonance imaging (MRI). Invasive tests such as a colonoscopy or an endoscopy can also help identify a causative medical condition. Differential Diagnoses Possible causes of diarrhea that need to be ruled out before a diagnosis of functional diarrhea is made include: Gastrointestinal (GI) infection, including chronic infection. Infections notoriously cause loose stools. Most GI infections last no longer than a few weeks and typically resolve on their own. But chronic infections, which can be diagnosed with a stool sample, may cause prolonged symptoms. Medication side effects. A number of medications can cause diarrhea, and you may develop this side effect even if you have taken medication for a while without diarrhea. Diet. Various food allergies and sensitivities can cause loose stools without pain. You may notice a pattern of diarrhea occurring after you eat certain foods. Celiac disease. This can develop with age and may be associated with gluten sensitivity, or may cause diarrhea regardless of your diet. Gluten sensitivity. This is becoming a more common problem. You can try a gluten-free diet for a few weeks to see if there is a decrease in your diarrhea. Lactose intolerance. A relatively common problem, lactose intolerance is characterized by diarrhea and cramping after eating or drinking dairy products. Fructose malabsorption. It can be more difficult to identify than lactose intolerance, but cutting out foods that contain fructose for a few weeks can help you assess whether fructose contributes to your diarrhea. Malabsorption due to bariatric surgery. Malabsorption is a common problem caused by bariatric surgery, in which parts of the GI system are removed to prevent over-eating and excessive absorption of calories. Gastrointestinal cancer. Cancer may cause bleeding and weight loss, and may manifest with a variety of less-common symptoms, such as diarrhea. Autonomic neuropathy. Often caused by chronic alcohol use, neuropathy can impair the function of nerves throughout the body, including the nerves of the GI system, potentially causing diarrhea. You may also be at higher risk of developing functional diarrhea after having your gallbladder removed. Treatment Typically, treatment of functional diarrhea is aimed at reducing symptoms through dietary modifications, such as eliminating possible trigger foods and slowly increasing fiber intake. If stress appears to be a possible contributing factor, stress-management strategies might be helpful. Your doctor may give you a prescription or recommendation for one of the following medications to reduce your diarrhea: An antidiarrhea medication like Imodium (loperamide) An antispasmodic medication A targeted antibiotic like Xifaxan (rifaximin) A bile acid binder like Questran (cholestyramine) An antidepressant to slow GI motility Was this page helpful? Thanks for your feedback! Gas pain? Stool issues? Sign up for the best tips to take care of your stomach. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Tack J. Functional diarrhea. 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Factor Analysis Defines Distinct Upper and Lower Gastrointestinal Symptom Groups Compatible With Rome IV Criteria in a Population-based Study. Clin Gastroenterol Hepatol. 2018 Aug;16(8):1252-1259.e5. doi: 10.1016/j.cgh.2018.02.042. Epub 2018 Mar 3.