Irritable bowel syndrome (IBS) is a medical condition characterized by altered bowel habits constipation or diarrhea, abdominal discomfort, bloating sensation etc without any functional abnormality, hence this disease is also is considered as functional gastrointestinal disorder (FGID).Depending upon the symptoms irritable bowel syndrome is of different subtypes namely diarrhea predominant (IBS –D), constipation predominant (IBS-C), pain predominant and altered bowel movement prominent (IBS-A).

Currently no drug can cure the symptoms of irritable bowel syndrome however treatment options include dietary modifications, prescription of drugs like antidiarrheal agents, anticholinergic, antispasmodic agents, antibiotic drugs etc and psychological therapy like counseling.The underlying cause of irritable bowel syndrome is not clearly identified yet however some possible theories are abnormal interaction between the brain and the digestive tract, alteration in the normal gut flora which may lead to the symptoms of irritable bowel syndrome.
Causes
As stated earlier the factors which may lead to irritable bowel syndrome is not known however there are several factors which might play an important role in causation of irritable bowel syndrome. Under normal circumstances the muscles of the gut lining the gut wall undergo contraction and relaxation in a coordinated way following entry of food from the stomach into the gut and during its propagation to the end portion of the gut, the rectum.

In patients suffering from irritable bowel syndrome these normal gut muscle contractions become aggravated both in terms of severity as well as duration leading to the different predominant symptoms of irritable bowel syndrome namely diarrhea, bloating sensation, abdominal distension, abdominal discomfort to frank abdominal pain etc. In contrast to aggravated gut muscle contracture in some patients the muscles of gut become abnormally relaxed leading to slowing of gut movement and delayed passage of food and stool resulting into another predominant symptom of irritable bowel syndrome, constipation.

In some of the patients of irritable bowel syndrome is thought to occur due to abnormal functioning of the nerves supplying the gut muscles leading to exaggerated response following stretching of the gut wall by stool or gas within normal limits.Sometimes in coordination in action between the nerves coming from the brain supplying the gut muscles may lead to symptoms of irritable bowel syndrome.There are several factors which may trigger the symptoms of irritable bowel syndrome in the susceptible persons.These factors include
1) Foods: although the exact association between allergy to certain food and susceptibility to irritable bowel syndrome is not clearly understood; but it is known that several people suffering from irritable bowel syndrome have aggravated symptoms of the disease following consumption of certain things namely chocolates, spices, some fruits, cabbage, cauliflower, broccoli, milk and milk products, alcohol, carbonated drinks etc.
2) Stress: exposure to stress may also lead to aggravation of the symptoms of irritable bowel syndrome, if not cause them.
3) Hormones: the incidence of irritable bowel syndrome is more in women and especially the symptoms aggravate during menstrual periods suggesting that hormone may play an important role in causation of irritable bowel syndrome.
4) Sometimes suffering from other diseases namely diarrhea due to infection (gastroenteritis), bacterial overgrowth in the gut may aggravate or trigger the symptoms of irritable bowel syndrome
Risk factors
Common risk factors include
1) Being female
2) Being below 45 years of age
3) Having family history of irritable bowel syndrome
4) Having mental problems
Treatment
As the underlying cause of irritable bowel syndrome is not clear the aim of treatment is to relieve the symptoms. In most of the cases with mild symptoms management of stress, avoidance of factors which trigger or aggravate the episodes of attack, adopting favorable life style and diet, adequate exercise, plenty of fluid intake and enough sleep are sufficient to relieve the symptoms.In people with moderate to severe symptoms of irritable bowel syndrome Certain dietary changes are recommended. These are
1) Reducing or complete stoppage of intake of high gas producing foods especially vegetables like cauliflower, broccoli, raw fruits, carbonated drinks etc.
2) Elimination of gluten containing foods namely wheat, barley, rye etc from the diet: as avoidance of these foods sometimes lead to improvement of symptoms of irritable bowel syndrome specially diarrhea.
3) Avoidance of certain carbohydrate foods (the fermentable oligo, di, monsaccharides and polyols also known as FODMAPs) may lead to relief of some symptoms of irritable bowel syndrome.
Certain drugs like fiber supplement like
1) psyllium, methylcellulose to control the symptoms of constipation
2) anti diarrheal drugs like loperamide etc to control diarrheal symptoms
3) anticholinergics and antispasmodic drugs like hyoscyamine, dicyclomine etc
4) antidepressant drugs: as anxiety, depression etc may aggravate symptoms of irritable bowel syndrome
5) antibiotics to control overgrowth of bacterial flora in the gut, if any
6) counseling may also be helpful
There are two medications approved for irritable bowel syndrome; these are alosetron and lubiprostone.