Dr Dafydd Bowen Gastroenterology

Irritable Bowel Syndrome (IBS)

IBS is a condition where the bowel causes unpleasant symptoms without any abnormality being demonstrated. There is no clear cause, but it can occur following a gut infection such as Salmonella or Campylobacter. Stress is also thought to contribute to the condition. Symptoms can vary and include diarrhoea, constipation, cramps and bloating. Often a combination of these may be present.

The diagnosis is often made once conditions such as coeliac disease, colitis and cancer have been excluded. Treatment plans are then made according to symptoms. My preferred treatment involves changes to the diet. Medicines have often been tried and failed prior to referral to a gastroenterologist.


The western diet is high in wheat. Removing wheat from the diet can often lead to an improvement in diarrhoea, bloating and gas production. The reason for this is unclear but it may be related to an intolerance to wheat in the small bowel, leading to carbohydrates being deposited in the large bowel. Carbohydrates in the large bowel are not absorbed and it will then either ferment leading to bloating or suck water in leading to diarrhoea.

If embarking on removing wheat I would suggest a fully wheat free diet for 1-2 weeks and should this be effective then a gradual re-introduction of wheat. This will help you find the amount of wheat that triggers your symptoms. Despite having a wheat intolerance you may still eat wheat but the more you eat of it the more likely and more severe the symptoms will be.


There are mixed views on fibre. Previously it was thought that fibre was a good treatment for IBS. It is now felt that the increased bulking of stools caused by fibre makes the cramps and pain of IBS worse. Pain in the left lower abdomen prior to emptying the bowels can often be improved by reducing fibre intake. The government's recent 5 a day plan and now 7 a day plan may improve general health but it can have the side effect of worsening IBS symptoms.


A lactose intolerance can lead to diarrhoea, bloating and abdominal pain. The reason for this is similar to wheat. A trial of removing lactose over 1-2 weeks usually leads to an improvement should you be lactose intolerant. Tests for lactose intolerance are available but access to these tests can be limited. Often a dietary trial of exclusion is more helpful.


Although not a cause of IBS it certainly makes symptoms a lot worse and may even unmask undiagnosed IBS. Often stress can't be removed easily but the above treatments on diet manipulation can still help during stressful times.

Drug treatment

Often GP's will try antispasmodics such as Mebeverine or Buscopan. These work for some but not for most. Drug treatment depends on particular symptoms.

Symptom Drug
Diarrhoea Loperamide, Codeine
Pain Antispasmodic, Amitryptilline antidepressants
Constipation Stimulant laxatives
Bloating Probiotics


If bloating is resistant to the above treatments, probiotics may be worth a try. They work by changing the bacteria in the colon hopefully reducing gas production. Supermarket probiotics are not strong enough to lead to improvements. VSL-3 is a strong probiotic. This is available at www.vsl3.co.uk. Some GP's are willing to prescribe. Other strong probiotics are available at health-food shops often at a more reasonable price.