Causes and Risk Factors

Chances are that if you’re reading this, you already know the discomfort that irritable bowel syndrome (IBS) can lead to. Cramping, bloating, and frequent trips to the bathroom can come on seemingly without warning.

You are not alone. The American College of Gastroenterology estimates that 10 to 15 percent of adults experience IBS at some point in their lives, but only half of those are diagnosed (ACG, 2012).

Being aware of the causes and risk factors for IBS may help you reduce the frequency of outbreaks and take steps toward prevention.

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Causes of IBS

Doctors still don’t fully understand what causes IBS, but most believe it to be the result of a combination of physical and mental health factors. Some issues believed to cause an IBS flare up include the following.

Brain-Gut Signal Problems

Messages sent from the brain to the intestines that are not being sent or received properly could cause the intestines to work differently during the digestive process and lead to cramping.

GI Motor Issues

The colon’s ability to move during digestion may be too slow—causing constipation—or too fast—causing diarrhea.


Someone with a lower pain threshold may feel the pain of bloating or cramping more than someone with a higher tolerance for pain.

Mental Health Problems

Stress can often aggravate physical ailments and IBS is no exception. Many doctors suspect a link between panic attacks or depression and IBS. However, whether mental health causes physical symptoms or simply exacerbates them is not known.

Bacterial Gastroenteritis

A bacterial infection within the intestines may lead to IBS symptoms.

Small Intestinal Bacterial Change

A change in the types of bacteria within the small intestine has been shown in some studies to cause excess flatulence and diarrhea.


Many women typically experience worsened IBS symptoms during their menstrual period. This leads some experts to believe that there is a connection between reproductive hormones and bowel problems. This theory is supported by evidence that many women also experience fewer IBS symptoms after menopause.


It is possible that IBS runs in families. However, whether this is due to a genetic link or to shared environmental factors remains unclear.

Food Sensitivity

Perhaps the most widely known IBS trigger is sensitivity to certain foods. Just as some people find that migraines tend to occur after eating particular foods, some people find that their intestinal distress increases with certain food intake.

Common problem-causing foods include:

  • coffee
  • alcohol
  • spicy foods
  • dairy products
  • overly fatty foods
  • carbohydrates

It is thought that the intestines may be unable to properly absorb certain components of these foods.

Risk Factors

According to the Mayo Clinic, certain demographics are more susceptible to IBS symptoms, including (Mayo, 2011):

  • those under 35: at least half of those with IBS first experience symptoms before the age of 35
  • women: more women than men are diagnosed with the condition
  • those with a family history of IBS: if a parent or sibling suffers from IBS, the likelihood increases that you will too

As mentioned earlier, researchers remain uncertain as to whether the family connection is due to genetics, shared environmental factors, or a combination of the two.