Irritable bowel syndrome (IBS)
Irritable bowel syndrome (IBS) is a mixture of abdominal symptoms for which there is no apparent cause.
Symptoms include constipation, diarrhoea, bloating and abdominal pain.
It is the most common condition seen by gastroenterologists and some estimates suggest that as many as one in five adults in the UK have IBS at any one time.
The bowel and IBS
Your bowel, or gut, extends from your stomach to your anus. It is made up of the small intestine and the large intestine. Their job is to process food from the stomach.
The small intestine absorbs nutrients from food and passes undigested food into the large intestine. In the large intestine, or colon, this waste product is processed into faeces.
The normal bowel moves food along the intestines through muscular contractions, known as propulsion. There are also areas of hold-up, known as segmentation.
This combination of propulsion and segmentation is called peristalsis. You are completely unaware of it when it is working normally.
The control of peristalsis is complex. The best way to regard IBS is as a loss of coordination of these muscular contractions.
In addition, there is evidence that people with irritable bowel syndrome have increased sensitivity within the gut to external stimuli such as stress.
This means IBS is often the outcome of a complex interaction between psychological and physical factors.
A disorder of the digestive system can affect the gut anywhere from the mouth to the anus, which accounts for the diversity of symptoms seen in IBS.
What causes irritable bowel syndrome?
We don't know what causes IBS.
- About half of people with IBS date the start of their symptoms to a major life event such as change of house or job, or bereavement. This suggests that there may be a psychological trigger for IBS.
- About 10 to 20 per cent of people will date the start of their symptoms to an acute gastroenteritis (inflammation of the stomach that causes vomiting and diarrhoea).
- In the remainder of cases, the trigger factor remains unidentified.
Abnormalities in peristalsis can often be seen in close relatives of people with IBS, although without symptoms. This suggests a trigger sets off the condition in susceptible people.
Nerve-signalling chemicals, particularly serotonin, appear to have an important role
What are the symptoms of IBS?
IBS symptoms and can start at any age, but are most common in late teenage years or early adulthood.
The four most common symptoms are:
- abdominal pain
- bloating that usually subsides overnight and returns the following day
You may experience problems in only one part of the gut or in several, and symptoms can change over time. Your symptoms will depend on which parts of the gut are involved.
Oesophagus (takes food from mouth to stomach)
- A sensation like a golf ball in the throat between meals, but does not interfere with swallowing.
- Heartburn - burning pain often felt behind the breastbone.
- Painful swallowing (odynophagia), but without hold-up of food.
- Sticking of food (dysphagia) - this requires investigation.
- Non-ulcer dyspepsia (symptoms suggestive of a stomach or duodenal ulcer, but which has not been confirmed on investigation).
- Feeling full after small meals. This may reach the stage of not being able to finish a meal.
- Abdominal bloating after meals.
- Increased gurgling noises which may be loud enough to cause social embarrassment (borborygmi).
- Severe abdominal bloating and generalised abdominal tenderness associated with bloating.
- Right-sided abdominal pain, either low or tucked up under the right ribs. Does not always get better after passing a stool.
- Pain tucked up under the left ribs (splenic flexure syndrome). When the pain is bad, it may enter the left armpit.
- Variable and erratic bowel habits alternating from constipation to diarrhoea.
- Flatulence (excess wind).
- Increased gastro-colic reflex. This is an awakening of the childhood reflex where food in the stomach stimulates colonic activity, resulting in the need to pass a stool.
- Severe, short stabbing pains in the rectum, called proctalgia fugax.
- In women, left-sided abdominal pain during sex.
- Passing urine more often.
- Fatigue and tiredness.
- Sleep disturbance.
- Loss of appetite.
- Depressive symptoms in about a third of patients.
- Anxiety and stress-related symptoms, which may interact with gut symptoms.
When should I see a doctor?
Because irritable bowel syndrome can mimic so many other intestinal disorders, you should see your doctor if you identify any of the following symptoms.
- Difficulty in swallowing when food gets stuck.
- Indigestion-type pain that wakes you up at night.
- Abdominal bloating that does not get better overnight.
- Significant and unexplained weight loss.
- Bleeding from the back passage.
- Chronic, painless diarrhoea.
This list is not comprehensive. If there are other symptoms, you should seek further advice.
In general, first-time symptoms of IBS in a person over the age of 40 should be assessed by a doctor.
How is irritable bowel syndrome diagnosed?
There is no single blood test, X-ray or scan that will diagnose IBS.
The diagnosis is often made on the basis that typical symptoms are present, particularly in younger people.
Blood may be taken to exclude other conditions, and occasionally further investigations are performed.
As people with IBS get older, more investigations are performed to ensure the diagnosis is correct. These may include:
- gastrosocopy - examination of the oesophagus, stomach and small intestine with a camera on the end of a long thin tube (endoscope).
- barium studies – a salt that shows up in X-rays of the stomach and intestines.
- colonoscopy - examination of the large intestine with an endoscope.
Is there anything I can do to prevent IBS?
Since the cause of IBS is unknown, it's not possible to reliably prevent symptoms.
The following strategies can help your digestive system and so may improve the condition.
- Drink lots of water, preferably two litres a day.
- A high-fibre diet improves digestion. The amount of fibre must be increased gradually to allow the stomach to get used to it.
- Avoid food or beverages that make the symptoms worse. Coffee and milk are frequent offenders.
- It may be helpful to keep a diary in which you note down the foods that seem to upset your stomach.
- Avoid strong spices and foods that give you wind.
- Avoid large meals, but eat regularly.
- Limit your alcohol intake.
What else can improve IBS?
- Physical activity and exercise can improve digestion and reduce stress.
- Heat treatment with hot packs, hot-water bottles or electric blankets may relieve stomach pain.
- Try to reduce the amount of stress in your life. You might like to experiment with some of the different relaxation techniques, such as meditation.
- Try to keep things in perspective: excessive worrying about digestive problems could lead to social and psychological problems.
Which medicines are used?
There is no single treatment to tackle all symptoms of IBS, although several types of serotonin antagonists are under trial, some with encouraging results.
Medicines can relieve specific symptoms of IBS, depending on which is giving you most trouble. But by controlling some symptoms, a medicine may make others worse.
- Medicines called antispasmodics can relieve stomach cramps. Examples are Spasmonal, Colofac, Buscopan and peppermint oil.
- If constipation is a major problem, bulk laxatives (Fybogel, Regulan, Isogel, Celevac) are usually tried first. More powerful types known as stimulant laxatives (Senokot, Dulco-lax) are not usually recommended for IBS because they can cause cramping.
- Fybogel mebeverine contains ispaghula husk and mebeverine. Ispaghula husk helps with constipation while mebeverine acts as an antispasmodic to relieve stomach cramps.
- Medicines can treat gas and stomach rumbling in cases where these are a major problem. Examples are charcoal tablets and simethicone, an anti-foaming agent that disperses trapped gas in the stomach and intestine. Products that contain simethicone are Wind-eze, Windsetlers and Rennie deflatine.
- Antidiarrhoeals such as loperamide (Imodium) can ease diarrhoea. Imodium plus also contains simethicone to ease cramps and bloating.
- Tricyclic antidepressants are sometimes used to relieve pain in people who have not responded to other treatments.
- Colestyramine (Questran) can help the small proportion of people with IBS whose diarrhoea is due to impaired handling of bile salts within the gut.
IBS usually occurs periodically throughout life. The symptoms can:
- get worse
- disappear for years.
Irritable bowel syndrome is not a life-threatening condition and cannot result in cancer or serious intestinal disease.
Treatment with medicines such as those mentioned above will normally ease symptoms.