Irritable Bowel Syndrome: Causes, Symptoms, and Treatments
Also known as: IBS, Spastic Colon, Irritable Colon
What is irritable bowel syndrome?
Irritable bowel syndrome (IBS) is a chronic functional digestive disorder characterized by abdominal pain combined with bowel habit changes, without any identifiable structural damage. About 12% of people in the United States have IBS, and women are up to twice as likely as men to develop it. It is most often found in people younger than 45. IBS can cause a great deal of discomfort, but it does not harm the intestines.
Causes and contributing factors
The exact mechanisms remain incompletely understood, and doctors believe a combination of problems leads to IBS rather than a single cause. Several factors are involved:
- Problems with brain and gut interaction, affecting how the digestive tract works
- Abnormalities in gut motility, where food moves too slowly or too quickly through the digestive tract
- Visceral hypersensitivity, where a normal amount of gas or stool in the gut is felt as pain
- Bacterial infections in the digestive tract, and small intestinal bacterial overgrowth
- Psychological factors, including stressful early life events, depression, and anxiety
- Genetic factors, which research suggests may increase susceptibility
- Food sensitivities, with certain foods causing digestive symptoms
Certain foods can trigger or worsen symptoms. More than half of people with IBS report food intolerances or symptoms that worsen with certain foods. FODMAPs, the carbohydrates that are hard to digest, are the target of the low-FODMAP diet, though the trial data so far is preliminary and one study found it no better than traditional dietary advice. Drinks that stimulate the intestines, such as coffee, tea, and colas, are often worth limiting, and many people with IBS report that fatty foods set off their symptoms too, though the evidence linking dietary fat to IBS is limited.
Symptoms
IBS shows up as recurring abdominal pain or discomfort, combined with bloating, and bowel changes that can alternate between diarrhea and constipation, or be predominantly one or the other. Symptoms are often relieved, at least partially, after a bowel movement, and can fluctuate with stress or diet.
Diagnosis
There is no single test that proves someone has IBS. Diagnosis relies on the Rome IV criteria, after ruling out other digestive conditions through history and clinical exam. Doctors look for a specific pattern: abdominal pain occurring at least once a week over the last 3 months, with symptoms starting at least 6 months earlier, plus at least two of the following:
- Pain related to bowel movements
- A change in how often you have bowel movements
- A change in the way your stools look
In most cases, doctors do not use tests to diagnose IBS. Additional testing may be offered in the presence of warning signs that suggest another condition, including unexplained weight loss, rectal bleeding, bloody or black and tarry stools, anemia, new symptoms later in life, or a family history of celiac disease, colon cancer, or inflammatory bowel disease. When ordered, testing can include bloodwork, stool tests, fecal calprotectin, a hydrogen breath test, upper GI endoscopy with biopsy, or colonoscopy.
Available treatments
Care is individualized and combines several approaches. You may have to try a few treatments to find what works best for you.
- Dietary adjustments, particularly a low-FODMAP diet, along with adding fiber. Your doctor may also recommend talking with a dietitian
- Antispasmodics to relieve abdominal pain, and enteric-coated peppermint oil capsules, which some evidence suggests can reduce IBS symptoms over the short term
- Bowel regulators tailored to the predominant pattern: laxatives for IBS with constipation, or antidiarrheals such as loperamide and eluxadoline
- Probiotics, where the evidence is not conclusive and some seem to work better than others
- Stress management (relaxation training, cognitive behavioral therapy) as a complement
Prevention
There is no known way to prevent IBS. Once you have it, lifestyle changes may help your symptoms: increasing your physical activity, reducing stressful life situations as much as possible, and getting enough sleep. Identifying the foods that set off your own symptoms is part of the same work, since food intolerances are common in IBS.
When should you see a doctor?
See a doctor for persistent symptoms, new symptoms starting at age 50 or older, unexplained weight loss, or blood in the stool, signs that call for further testing. If in doubt, do not hesitate to see a doctor quickly.
Key takeaway: Irritable bowel syndrome is a chronic functional condition that causes real discomfort but does not harm the intestines. Care combines diet changes, stress management, and medicines aimed at your main symptoms, and you may have to try a few treatments to find what works best for you.
Sources
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), U.S. national institute information on IBS definition, symptoms, diagnosis, treatment, and diet
- NIDDK, IBS definition and facts, the 12 percent US prevalence and women being up to twice as likely as men
- NIDDK, eating, diet, and nutrition for IBS, the low-FODMAP diet, fiber, and talking with a dietitian
- NIDDK, IBS treatment, antispasmodics, laxatives, loperamide and eluxadoline, and the lifestyle changes that may help symptoms
- MedlinePlus, IBS being most often found in people younger than 45 and not harming the intestines
- MedlinePlus Medical Encyclopedia, irritable bowel syndrome, symptom relief after a bowel movement and limiting drinks that stimulate the intestines
- StatPearls, Irritable Bowel Syndrome (NIH National Library of Medicine Bookshelf), the Rome IV criteria, red flag features including new symptom onset at 50 or older, and fecal calprotectin to exclude inflammatory bowel disease
- National Center for Complementary and Integrative Health (NCCIH), irritable bowel syndrome, evidence on probiotics and peppermint oil
- Addressing the Role of Food in Irritable Bowel Syndrome Symptom Management (PMC), self-reported food intolerance in more than half of patients, coffee and fat as reported triggers, and the preliminary state of the low-FODMAP evidence
- American College of Gastroenterology (ACG), IBS as a disorder of gut-brain interaction, the absence of a single test that proves IBS, and individualized treatment