The precise cause of irritable bowel syndrome is unknown.  It may result from:

• Abnormal contractions of the muscles in the intestinal walls-   The colon, which is about 6 feet long, connects the small intestine with the rectum and anus. The major function of the colon is to absorb water and salts from digestive products that enter from the small intestine. Two quarts of liquid matter enter the colon from the small intestine each day. This material may remain there for several days until most of the fluid and salts are absorbed into the body. The stool then passes through the colon by a pattern of movements to the left side of the colon, where it is stored until a bowel movement occurs. Colon motility is controlled by nerves and hormones and by electrical activity in the colon muscle. Movements of the colon propel the contents slowly back and forth but mainly toward the rectum. A few times each day strong muscle contractions move down the colon pushing fecal material ahead of them. Some of these strong contractions result in a bowel movement.

• An increased sensitivity to certain foods, such as fruit, sorbitol (an artificial sweetener), and fat, may also contribute.  Chocolate, milk products, or large amounts of alcohol are frequent offenders. Caffeine causes loose stools in many people, but it is more likely to affect those with IBS. In some cases, simply eating a large meal will trigger symptoms.

• The disorder sometimes develops after a gastrointestinal infection.

• Heredity: The problem can run in families, which suggests that genetic factors are involved. There are certain ethnic groups, such as Ashkenazi Jews, who are more likely to have the condition than others. And finally, there's been a recent discovery of a gene called the nod-2 gene, which is twice as likely to occur in Crohn's patients than in patients who do not have the disease.

• Stress, anxiety, and depression are associated with the syndrome and can make symptoms worse.

• Researchers also have found that women with IBS may have more symptoms during their menstrual periods, suggesting that reproductive hormones can increase IBS symptoms.

In fact, the bowel can overreact to all sorts of things, including food, exercise, and hormones.
 

The symptoms are typically intermittent but usually recur for many years and often persist into old age.  They vary widely among people and with each episode.  The main symptoms include :

• Abdominal bloating combined with excessive quantities of wind.

• Abdominal pain, often on the lower left side, that may be relieved by defaecation or passing wind.

• Diarrhoea, which may be most severe on waking and sometimes alternates with bouts of constipation that may produce "rabbit pellet" stools.

• Feeling that the bowel has not been emptied completely.

• Passage of mucus during defaecation.

• Nausea and vomiting.

• Feeling of fullness and difficulty in finishing meals.

Many people have symptoms unrelated to the digestive tract, such as tiredness, headache, back pain, and an increased urge to pass urine.  In women, sexual intercourse may be painful, and symptoms may be worse before menstrual periods.

You should consult your doctor if the symptoms are severe, persistent, or recurrent of if you have unexpectedly lost weight.  If you are over 40 when the symptoms develop, you should seek medical advice so that serious disorders with similar symptoms, such as colorectal cancer , can be ruled out.
 

There is no single test to diagnose irritable bowel syndrome.  Instead, your doctor will want to make sure that you have no other serious condition.  The type and number of tests used to investigate the disorder depend on your age.

If your symptoms suggest that you may have an inflammatory bowel disorder such as Crohn's disease  or if you are over the age of 40, your doctor will probably want to investigate your symptoms further. 

• Physical exam

• You may have a blood test to check for inflammation, which can indicate the presence of Crohn's disease. 

•  X ray of the bowel: This x-ray test is called a barium enema or lower GI (gastrointestinal) series. Barium is a thick liquid that makes the bowel show up better on the x ray. Before taking the x ray, the doctor will put barium into your bowel through the anus.

• Endoscopy: The doctor inserts a thin tube into your bowel. The tube has a camera in it, so the doctor can look at the inside of the bowel to check for problems.

• You may also have tests to exclude food intolerance  and lactose intolerance , which cause symptoms similar to those of irritable bowel syndrome.

Although the symptoms can be distressing, irritable bowel syndrome is not a serious condition.  You should usually be able to control your symptoms with a combination of a change in diet and relaxation techniques.  However, if symptoms are troublesome enough to interfere with daily routines, you should consult your doctor for advice on treatment. 

In terms of the medical treatments, the first group of drugs is called the aminosalicylates, or 5-ASA agents. These include drugs such as sulfasalazine, mesalamine, balsalazide and olsalazine, and they're good for treating mild to moderate disease. When the disease becomes more severe, often steroids are used. Steroids can be given intravenously or orally. The traditional oral drug had been prednisone, but more recently a new medication called budesonide was released which had similar efficacy but fewer side effects than prednisone.

You may be given antispasmodic drugs to relax the contractions of the digestive tract and help to relieve abdominal pain .  Your doctor may also prescribe antidiarrhoeal drugs to help to alleviate diarrhoea, especially if you have diarrhoea on waking.  If you regularly have problems with constipation, bulk-forming agents  may help.

If you have psychological symptoms such as anxiety in addition to irritable bowel syndrome, you should ask your doctor to refer you to a therapist for advice on how to control anxiety.

Irritable bowel syndrome tends to be a long-term disorder, often lasting into old age.  However, attacks usually become less frequent and severe with time.
 

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