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This is a very common disorder; 10–20% of the general population have symptoms consistent with Irritable Bowel Syndrome (IBS). Symptoms are usually a combination of abdominal pain and bowel problems—constipation or diarrhea, or both. Although IBS is a chronic condition, life expectancy is not decreased by having this condition. Individuals do not die from IBS; however, in some cases it can be challenging for both the patient and the doctor. For most sufferers, it is more of a quality-of-life issue.


There are many theories regarding the causes of IBS and—when there are many theories—it usually means that we do not know the cause yet. Some theories hold that bowel spasms are important, other theories suggest that the bowels are hyper-sensitive. Studies have been performed in which a balloon is blown up in both individuals with IBS and those without IBS. Individuals with IBS were first aware of the balloon blowing up at a much smaller volume and had to have the balloon inflation stopped at a smaller volume than individuals without IBS. This suggests that their bowels were ‘more sensitive’. Often, individuals with IBS will find that eating certain foods can worsen or exacerbate their symptoms. Certain foods cause increased gas production, discussed later.

Stress is a common factor that worsens IBS symptoms. There is a higher incidence of anxiety disorders in individuals with IBS. There is also a higher incidence of a history of abuse (physical, sexual or psychological). Some individuals have never had problems with IBS until after a bad intestinal infection (post-infectious IBS).


Typical symptoms are abdominal pain, usually described as ‘crampy’. Pain is often worse after eating and better after having a bowel movement. Some women find that their symptoms are worse or better during certain times of their menstrual cycle.

Bowel problems are also typical, including diarrhea or constipation, or a combination of alternating episodes of either. Individuals may have pellet-like stools. Sometimes after going to the bathroom there will be a sensation that the bowel movement has not been completely evacuated or that 15 to 30 minutes after a bowel movement it is necessary to attempt to go again. Often there is increased mucous in bowel movements as well as bloating. It is common to feel better a having an effective bowel movement.


Depending on symptoms, sometimes tests are required to rule out other possible causes of IBS such as Crohn’s disease, Ulcerative Colitis or other types of bowel inflammation. Some intestinal infections or problems with absorption can mimic IBS. In individuals with IBS, these tests are negative or normal. Sometimes more invasive tests such as a colonoscopy are required, particularly in older individuals. IBS is often referred to as a diagnosis of exclusion, in that other causes may need to be ruled out before IBS can be diagnosed.


The main thrust of treatment is reassurance (i.e. that there is nothing more serious such as cancer), along with trying to palliate or decrease symptoms so patients can get on with their lives or have their lives less affected by IBS symptoms.

Fiber is another cornerstone of treatment. Increasing dietary fiber intake often helps an individual with constipation or, in individuals with alternating diarrhea and constipation, helps them become more regular. Sometimes even in individuals who predominantly have diarrhea, ‘bulking up’ of their stools will cause them to have more significant and less frequent bowel movements which can help. That is not always the case; some individuals with diarrhea do better with medication that slows down or decreases diarrhea, such as Loperamide (Imodium®) or Lomotil®.

The introduction of fiber supplements like Psyllium (Metamucil) needs to be done slowly, and an individual needs to be on enough Psyllium to see a benefit. A teaspoon of Psyllium or Metamucil is usually not enough; often individuals need a couple of tablespoons per day. As the individual slowly increases fiberit can sometimes cause increased bloating and gas. If this is done slowly (over the course of 6-8 weeks), the individual usually builds up a tolerance, with the benefit of having more regular bowel movements. Sometimes individuals reach a certain amount and, as they increase it more, there is no further benefit and they may be worse (increased gas and bloating). It is important to try to get on a significant amount of Psyllium and give it a good try before giving up.

In some individuals, certain foods can exacerbate problems. If these foods are decreased, things can improve; however, one has to be careful about eliminating foods from the diet. Sometimes the individual tries to remain on a very limited diet (i.e. boiled chicken and rice), which is not advisable from a nutritional perspective.

If enough of certain foods such as coffee, other caffeine-containing beverages, peaches, prunes, pears and apples are ingested, they will cause diarrhea. In individuals who are already predisposed to diarrhea, it will take less of these foods to cause diarrhea. Some individuals have lactose or dairy intolerance contributing to their symptoms and it may be worthwhile to try eliminating lactose-containing products for 2 weeks to see if this helps. Some foods naturally cause increased gas and bloating, such as broccoli, cauliflower and cabbage; individuals with IBS can be more sensitive to these effects.

In individuals for whom anxiety exacerbates symptoms, dealing with that aspect can decrease or improve the IBS symptoms. It is not uncommon for individuals to have a previous history of abuse (physical, sexual or psychological). Sometimes this is in the remote past. Often if this issue is explored or dealt with, the IBS symptoms will improve.

Many tricyclic antidepressants (TCAs) such as Amitriptyline and Desipramine relieve or decrease IBS symptoms. The dosage of TCA used for IBS patients is much lower than that typically used in treating depression. In IBS they are not believed to work as antidepressants but as agents that possibly reduce pain perception. Some of these medications also cause constipation; therefore, when diarrhea is the predominant IBS symptom they act effectively on more than one level — decreasing diarrhea and the perception or intensity of pain.

Probiotics or ‘healthy bacteria’ (Acidophilus) are very popular and trendy at the moment. There are no studies to prove any benefit in IBS. This being said, some individuals do report that probiotics help.