A combination of intermittent abdominal pain, constipation, and/or diarrhoea
Irritable bowel syndrome accounts for more referrals to gastroenterologists than any other disorder, although many affected people never consult a doctor. The condition most often develops in people between the ages of 20 and 30 and is twice as common in women as in men. As many as 2 in 10 people have symptoms of irritable bowel syndrome at some time in their lives. The symptoms, which include abdominal pain, constipation, and/or diarrhoea, tend to be intermittent but typically persist for many years. Although irritable bowel syndrome can be distressing, it does not lead to serious complications.
The precise cause of irritable bowel syndrome is unknown. It may result from abnormal contractions of the muscles in the intestinal walls. An increased sensitivity to certain foods, such as fruit, sorbitol (an artificial sweetener), and fat, may also contribute. The disorder sometimes develops after a gastrointestinal infection (see Gastroenteritis). The problem can run in families, which suggests that genetic factors are involved. Stress, anxiety, and depression can be associated with the syndrome and may make symptoms worse.
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 defecation 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 defecation.
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 or if you have unexpectedly lost weight. If you are over 40 when the symptoms first 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 for irritable bowel syndrome and the diagnosis is made on the basis of your symptoms, medical history, and often tests to exclude other possible disorders. 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. You may have a blood test to check for inflammation, which can indicate the presence of Crohn’s disease. If the result is positive or if your doctor suspects a colorectal tumour, you will probably have a contrast X-ray of the intestines or undergo a colonoscopy. 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 be able to control your symptoms with a combination of a change in diet and relaxation techniques (see Living with irritable bowel syndrome). However, if symptoms are troublesome enough to interfere with daily routines, you should consult your doctor for advice on treatment. You may be given antispasmodic drugs to relax the contractions of the digestive tract and help to relieve abdominal pain (see Antispasmodic drugs and motility stimulants). 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 (see Laxatives) may help.
If you have psychological symptoms such as anxiety or depression in addition to irritable bowel syndrome, your doctor may refer you to a therapist for advice on controlling them.
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.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.