What Is Irritable Bowel Syndrome (IBS)?

Medically Reviewed by Sabrina Felson, MD on January 26, 2020

The mornings with irritable bowel syndrome are the most challenging for Jeffrey Roberts. His stomach cramps up. He feels like he needs to be near a bathroom at all times. So he gives himself at least 2 hours to get ready for work. When he goes out, he often takes routes he knows will have public restrooms along the way.

This is reality for Roberts and up to 20% of American adults who suffer from irritable bowel syndrome (IBS) at some point in their lives. Their exact symptoms, and the severity, may differ. But for people with IBS, daily life is greatly influenced by the way their digestive system behaves. A flare-up of symptoms can mean hours of misery.

"IBS is an illness which seems to strike people down," says Roberts, president of the IBS Self Help and Support Group.

What causes these recurring symptoms of abdominal pain, bloating, gas, diarrhea, or constipation?

Doctors don't have a clear picture what IBS is or what causes it. But researchers do have a few theories:

  • IBS sufferers may have a more sensitive colon than others.
  • In people with IBS, the brain may perceive contractions in the gut more acutely than others.
  • The immune system may respond differently to stress and infection in people with IBS.
  • Hormonal changes may trigger IBS symptoms (70% of those who suffer from IBS are women).
  • The neurotransmitter serotonin that is produced in the gut may act on digestive tract nerves. Those with diarrhea may have increased serotonin levels in the gut, while those with constipation-predominant IBS have decreased amounts.

Though no one fully understands what causes IBS, doctors do agree that IBS is a bona fide medical condition. They do not think it's "all in your head." According to the American College of Gastroenterology, IBS is also clearly defined by what it is not:

  • It is not an anatomical or a structural problem.
  • It is not an identifiable physical or chemical disorder.
  • It is not a cancer and will not cause cancer.
  • It will not cause other gastrointestinal diseases.

Basically, IBS is a collection of symptoms that has been ongoing for at least 6 months, and has occurred at least 3 times a month in the past 3 months. IBS always involves abdominal pain or discomfort. This pain must have two of these three characteristics to be diagnosed IBS:

  • Relieved with defecation
  • Associated with a change in frequency of stool
  • Associated with a change in form (appearance) of stool

Certain foods or situations may trigger a flare-up of IBS symptoms. People with IBS can keep a symptom journal to figure out what triggers their illness and how best to avoid those triggers.

If you think you may have IBS, see your doctor for proper diagnosis and care. Depending on the type of IBS that you have, there are various treatment options, including dietary changes, stress management, medication, behavioral therapy, and alternative treatments.

"It's a matter of trying to live with your symptoms rather than having your symptoms take over your life," says Roberts.

WebMD Medical Reference



Jeffrey Roberts, president and founder, IBS Self Help and Support Group. 

American College of Gastroenterology. 

Mayo Clinic. 

National Digestive Diseases Information Clearinghouse.

Harvard Health Publications: "Understanding and treating an irritable bowel."

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