Irritable bowel syndrome (IBS) is characterised by a mixture of symptoms that are believed to be due to a disorder of intestinal Qi function.

The commonest condition seen by gastroenterologists.
Normal gut moves food along the gut through muscular contractions, known as propulsion. There are also areas of hold-up, known as segmentation.

Other names for IBS
Some old-fashioned names for IBS are:
irritable colon
spastic colon
mucous colitis.

These are misleading because IBS also affects the remainder of the gut.

The 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.

There is evidence that patients with irritable bowel syndrome have increased sensitivity to stimuli arising within the gut.

As well as the intestinal symptoms, psychological factors are often involved. This is not to say these symptoms are not real (they are), but IBS is often the outcome of a complex interaction between psychological and physical factors.

A gut function disorder can affect the gut anywhere from the mouth to the anus, which accounts for the diversity of symptoms seen in IBS.

How common is IBS? About half of all people will date the start of their symptoms to a major life event such as change of house or job and others exiting events. This suggests that there may be a psychological trigger in susceptible patients. About 10 to 20 per cent of people will date the start of their symptoms to an acute gastroenteritis. 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.

Oesophagus
A sensation like a golf ball in the throat between meals which does not interfere with swallowing (globus).
Heartburn - burning pain often felt behind the breastbone.
Painful swallowing (odynophagia), but without hold-up of food.
Sticking of food (dysphagia) - this requires investigation.

Stomach
Non-ulcer dyspepsia .
Feeling full after small meals. This may reach the stage of not being able to finish a meal.
Abdominal bloating after meals.

Small bowel
Gurgling noises which may be loud enough to cause social embarrassment (borborygmi).
Abdominal bloating which may be so severe that women describe themselves as looking pregnant.
Generalised abdominal tenderness associated with bloating.
Abdominal bloating of both types usually subsides overnight and returns the following day.

Large bowel
Other symptoms
Headaches.
In women, abdominal pain during sex.
Passing urine more often.
Fatigue and tiredness.
Sleep disturbance.
Loss of appetite.
Nausea.
Depressive symptoms in about a third of patients.
Anxiety and stress-related symptoms, which may interact with gut symptoms.

Abdominal bloating of both types usually subsides overnight and returns the following day.
Right-sided abdominal pain, either low, or tucked up under the right ribs. Does not always get better on opening the bowels.
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.
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 open the bowels.
Severe, short stabbing pains in the rectum, called proctalgia fugax.