What is IBS?

Irritable bowel syndrome (IBS) is a chronic and potentially debilitating chronic bowel disorder. It is often a diagnosed when investigations have not shown any evidence of structural, biochemical or inflammatory disease.

What is the cause of IBS?

The precise cause or causes of IBS are unknown but it is thought to be due to effects on the gut and brain pathway, between which there are thought to be strong links. There are thought to be a number of various factors involved in the development of IBS including:

Possible triggers including infections, inflammation, food antigens and medications

Changes in intestinal permeability (‘leaky gut’)

Changes in gut microbiome (the bacteria species which reside in the gut)

Changes in central nervous system function

What are the Symptoms of IBS?

Current criteria (Rome IV) define IBS as abdominal pain related to defecation or with a change in stool form or frequency. Patients often report predominant diarrhoea or constipation although both can co-exist and bloating is a frequently accompanying symptom. IBS is rare in patients over the age of 50 years and the presence of ‘alarm symptoms’ such as rectal bleeding, weight loss, anaemia, strong family history of cancer or inflammatory bowel disease (IBD) should not be diagnosed as IBS and require investigation.

How does it impact on routine life?

IBS has a great impact on quality of life and work productivity. It affects approximately 10% of the general population and most commonly affects young people particularly women. Patients often feel anxious and depressed and unable to carry out daily tasks.

What are the available tests?

IBS should be diagnosed by clinical features and basic investigations. These include:

Blood tests including full blood count, C-reactive protein, coeliac serology tests and liver function tests.

Faecal calprotectin samples are a very useful marker of intestinal inflammation. A negative result makes the diagnosis of IBS very likely.

Stool microscopy & culture sensitivity samples can be useful to check for infections such as gastroenteritis. Gut infections can lead to post-infectious IBS.

Endoscopy tests include gastroscopy and lower gastrointestinal endoscopy constituting flexible sigmoiodoscopy and colonoscopy. These are invasive tests and so may no be required usually being reserved for equivocal or difficult cases.

Radiological tests include abdominal ultrasound and CT scanning. These may be performed to check for other causes of abdominal pain such as gallstone disease and diverticulitis.


IBS can affect different individuals in different ways leading to a constellation of symptoms. Treatment plans need to be tailored to individual patients. Dietary modification is one of the first interventions that can be tried. This includes:

Low FODMAP diet involves eliminating particular fermentable carbohydrates and then systematically re-introducing them into the diet.

Increase soluble fibre intake (eg. Psyllium) and reduce insoluble fibre intake.

Psychological counselling may be effective for certain individuals with abdominal pain.

Medical Treatment

The right drug needs to be selected to help specifically target and treat the patient’s symptoms. A trial and error approach may need to be adopted with different drugs combined to improve their effectiveness.

Probiotics may be effective but more robust evidence is needed to prove their effectiveness.

Antispasmodic drugs may be effective for abdominal pains and particularly spasm-type pains.

Peppermint oil has been shown to be a siple treatment that is effective for most IBS symptoms.

Linaclotide is a drug which has been shown to be effective in reducing abdominal pain and improve constipation.

Prucolapride is a drug which has been shown to be effective in treating young women with IBS and constipation.

Eluxadoline is a relatively new drug which has been shown to be effective in treating IBS with diarrhoea symptoms.

Rifaxamin is an antibiotic treatment which has been shown to possibly improve IBS symtpoms.

Amitriptylline is a drug which acts on the nervous system and acts as a nerve painkiller. It has been shown to help improve IBS symptoms particularly abdominal pain.

Date: 31/10/2017