Irritable Bowel Syndrome (IBS)

What IBS is

Irritable bowel syndrome (IBS) is a group of symptoms that occur together: repeated belly pain and changes in bowel movements, which may be diarrhea, constipation, or both. With IBS, there are no visible signs of damage or disease in the digestive tract. [1] Doctors now call IBS a disorder of gut-brain interaction, meaning the brain and gut do not work together as they should, which can make the gut more sensitive and change how bowel muscles contract. [1]

Studies suggest that about 12 percent of people in the US have IBS. Women are up to two times more likely than men to develop it, and it is more common in people younger than 50. [1] IBS is usually long-lasting, but symptoms come and go. [2] It can be painful but does not damage the digestive tract or lead to other health problems. [2] Other symptoms can include bloating, a feeling that a bowel movement is not finished, and whitish mucus in the stool. [2]

IBS subtypes

Three types are based on the pattern of abnormal stools: IBS with constipation (IBS-C), IBS with diarrhea (IBS-D) and IBS with mixed bowel habits (IBS-M). [1] Some treatments work only for some types or make other types worse. [1]

IBS is not the same as IBD, celiac disease or lactose intolerance

Several conditions share symptoms, so an accurate diagnosis matters.

How IBS is diagnosed

In most cases doctors do not use tests to diagnose IBS. They look for a pattern: belly pain together with two or more of these: pain related to bowel movements, a change in how often you go, or a change in how stools look. They also ask how long you have had symptoms. [9] Doctors may order blood or stool tests, and sometimes a breath test, upper endoscopy or colonoscopy, to rule out other conditions. [9] The American College of Gastroenterology suggests blood testing for celiac disease in people with IBS and diarrhea symptoms. [10]

Symptoms that point to another problem rather than IBS include anemia, bleeding from the rectum, bloody or black tarry stools, and weight loss. [9]

What the research shows about common approaches

An umbrella review of nutrition trials concluded that most dietary interventions showed small effects with low or very low certainty, except probiotics and a low-FODMAP diet, which had moderate-certainty evidence for some outcomes over short follow-up. [19]

Evidence labels: established recommendation = a guideline or health agency recommends it; promising but limited = some positive human studies that are small or uncertain; mixed = studies or sources disagree.

Medicines and professional care

Doctors may suggest medicines for particular IBS types, such as loperamide or rifaximin for IBS-D, or fiber supplements, laxatives, lubiprostone, linaclotide or plecanatide for IBS-C. Antispasmodics, low-dose antidepressants and coated peppermint oil capsules may be used for pain. [18] Always take medicines as instructed and do not stop a prescription on your own. See heartburn, reflux and GERD when upper-gut symptoms overlap.

Before using probiotics, herbal products or other supplements, talk with your doctor, especially if you take other medicines. [18] Read how interactions work. See also probiotics and prebiotics for gut health and psyllium, ginger and peppermint.

When to get help

See a clinician for a new or changing bowel pattern, and promptly for rectal bleeding, black or bloody stools, anemia, unplanned weight loss, or severe or constant pain, because these may signal something other than IBS. [9] NHS guidance lists blood in stool, a lump in the belly, and unexplained weight loss among bowel cancer warning signs that need checking. [20] See digestive symptoms: red flags. In the US, call 911 in an emergency.