Irritable Bowel Syndrome (IBS)

A woman finding information about IBS.

About Irritable Bowel Syndrome (IBS, formerly “spastic colon”)

Why it is Problematic

Causes and Risk Factors





About Irritable Bowel Syndrome (IBS, formerly “spastic colon”)

Irritable bowel syndrome (IBS) is a common chronic “functional” gastrointestinal disorder that affects bowel habits, but does not physically affect the structure of the GI tract. IBS shares some common symptoms with IBDs (Crohn’s disease and ulcerative colitis) but is markedly different in that IBS does not cause chronic inflammation, intestinal obstruction, scarring and/or create a higher risk of developing colon or GI cancer. Although there is a lack of visibly detectable indications of IBS in the digestive system, various disruptive symptoms can manifest, such as altered GI function and/or chronic pain and discomfort. Researchers believe that IBS, and other functional GI disorders are somehow linked to the autonomic nervous system, which is the body’s “second brain”. The exact role that this brain-gut axis plays in IBS is not entirely understood.


Why it is problematic

IBS is problematic in that the symptoms are often painful and may cause a great deal of discomfort. Compared to the general population, individuals with IBS have a higher incidence of depression and anxiety. The medical community once believed that anxiety and depression was the cause of IBS, however; now some researchers are investigating the possibility that IBS causes anxiety and depression. Examination of the links between IBS and neurological/psychological symptoms are still underway. IBS is a major cause of workplace absence due to the unpleasant symptoms.


Causes and Risk Factors

The precise cause of IBS is unknown. However, several theories exist about the potential causes of the syndrome. Some theories include the possibility of overactive nerves in the GI tract as well as impaired brain-gut activity. Food intolerance, bacterial overgrowth or abnormal gut flora, pain sensitivity, unidentified infections, and changes in metabolism of the brain chemical serotonin are other possible causes or contributors. Stress does not appear to cause IBS, however, it can cause symptom aggravation.

There are substantially more reported cases of IBS in women than in men. Nevertheless, it is likely that men less frequently seek medical attention for IBS than women. IBS appears to have a genetic link, as it is more common to have IBS if a family member does. Research indicates that symptoms of IBS seem to change in accordance to a woman’s menstrual cycle, which may indicate a hormonal influence. Some reports indicate that sexual trauma may also be a risk factor in the development of IBS.



IBS symptoms vary depending on the subcategory of the disorder. There are four IBS subcategory classifications as defined by and individual’s bowel habits. These classifications include:

• IBS with constipation (IBS-C), impaired bowel habits with a tendency to become constipated. This the most common type of IBS.
• IBS with diarrhea (IBS-D), impaired bowel habits with a tendency to experience diarrhea.
• Mixed IBS (IBS-M), impaired bowel habits that alternate between constipation and diarrhea.
• Unsubtyped IBS (IBS-U)

Abdominal pain and/or abdominal discomfort are the most common symptoms among all subtypes of IBS. This pain can fluctuate in duration, severity and bodily location. Eating sometimes intensifies this pain. Typically pain subsides after a bowel movement.

Stool changes are an identifying characteristic of IBS. These changes can include constipation, diarrhea or a mixture of both. Normal bowel movements are typically regarded as those that do not involve constipation or diarrhea, but there is sometimes confusion about the medical definitions of these conditions.

Constipation is defined as:
Fewer than three bowel movements per week
Bowel movements small, hard, dry
Painful or difficult to pass
Abdominal bloating

Diarrhea* is defined as:
Three or more bowel movements per day
Loose or watery stools

*Please not that adults should visit a doctor if diarrhea persists longer than 48 hours and longer than 24 hours for children.

Individuals with IBS may suffer bouts of constipation, bouts of diarrhea or have alternating periods of constipation and diarrhea.

Mucus may be visible in the stool.

Incomplete gastric emptying, or the feeling of not completely emptying stool from the rectum

Urgency to use the restroom

Other symptoms of IBS include:
• Heartburn
• Early satiety (feeling full with little food)
• Nausea
• Abdominal fullness
• Bloating
• Dyspepsia (upper abdominal pain)
• Fatigue
• Malaise
• Muscle pain
• Sleep disturbances
• Sexual dysfunction
• Lower back pain
• Headache

Women with IBS report more gynecological issues including:
• Dysmenorrhea (pain/cramping with menstruation)
• Premenstrual distress syndrome
• Insomnia
• Food sensitivity
• Chronic pelvic pain



There is no singular test that can diagnose IBS. Usually, a series of diagnostic tests are performed to rule out the presence of other gastrointestinal disorders or diseases. Symptoms of many GI conditions are similar therefore, it is important to rule out other conditions such as Crohn’s disease and ulcerative colitis. These diagnostic tests might include:

Stool samples are often requested. This sample can reveal if there is another cause for the symptoms. These causes could include bacteria and infection.

Blood testing is routine in identifying GI conditions. A Full Blood Count test is given to assess general health as well as look for anemia (the lack of iron in the blood). Anemia is not associated with IBS but is associated with IBD. Blood tests will also look for indications of inflammation in the body.

Once other conditions are ruled out, typically no further tests are necessary and a diagnosis of IBS is made.



Lifestyle and behavior modification are often necessary for the treatment of IBS. These include toxin avoidance, exercise, stress-management, and diet modification.

Diet recommended for individuals with IBS include following a low FODMAP diet, eating regularly, avoiding carbonated beverages, limiting caffeine and alcohol, and drinking plenty of water.

Medication is sometimes given to manage symptoms. These may include laxatives for individuals with constipation, anti-diarrheal medication for individuals with diarrhea, tricyclic antidepressants, SSRI antidepressants, pain medication and medication to treat bloating.

Cognitive behavioral therapy (CBT) has hailed successful results for many individuals suffering from IBS. This treatment helps redefine patterns of thinking.



It is estimated that between 10 and 15% of the U.S. population and between 9 and 23% of the global population has IBS. IBS affects people of all ages, including children, but is diagnosed predominately before the age of 50.

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