Irritable bowel syndrome (IBS) is a chronic, relapsing and often life‑long disorder. It is characterised by the presence of abdominal pain or discomfort, which may be associated with defaecation and/or accompanied by a change in bowel habit. Symptoms may include disordered defaecation (constipation or diarrhoea or both) and abdominal distension, usually referred to as bloating. Symptoms sometimes overlap with other gastrointestinal disorders such as non‑ulcer dyspepsia or coeliac disease. People with IBS present to primary care with a wide range of symptoms, some of which they may be reluctant to disclose without sensitive questioning.
National Institute for Health and Care Excellence, UK (NICE) has updated the guidelines on Irritable bowel syndrome in adults: diagnosis and management in April 2017. Following are the major recommendations:
1.1 Diagnosis of IBS
Confirming a diagnosis of IBS is a crucial part of this guideline. The primary aim should be to establish the person’s symptom profile, with abdominal pain or discomfort being a key symptom. It is also necessary to establish the quantity and quality of the pain or discomfort, and to identify its site (which can be anywhere in the abdomen) and whether this varies. This distinguishes IBS from cancer‑related pain, which typically has a fixed site.
When establishing bowel habit, showing people the Bristol Stool Form Scale may help them with description, particularly when determining quality and quantity of stool. People presenting with IBS symptoms commonly report incomplete evacuation/rectal hypersensitivity, as well as urgency, which is increased in diarrhoea‑predominant IBS. About 20% of people experiencing faecal incontinence disclose their incontinence only if asked. People who present with symptoms of IBS should be asked open questions to establish the presence of such symptoms (for example, tell me about how your symptoms affect aspects of your daily life, such as leaving the house’).
1.1.1 Initial assessment
18.104.22.168 Healthcare professionals should consider assessment for IBS if the person reports having had any of the following symptoms for at least 6 months:
- Abdominal pain or discomfort
- Change in bowel habit. 
22.214.171.124 All people presenting with possible IBS symptoms should be assessed and clinically examined for the following ‘red flag’ indicators and should be referred to secondary care for further investigation if any are present:
- signs and symptoms of cancer in line with the NICE guidance on recognition and referral for suspected cancer
- inflammatory markers for inflammatory bowel disease .
126.96.36.199 This recommendation has been withdrawn .
188.8.131.52 A diagnosis of IBS should be considered only if the person has abdominal pain or discomfort that is either relieved by defaecation or associated with altered bowel frequency or stool form. This should be accompanied by at least two of the following four symptoms:
- altered stool passage (straining, urgency, incomplete evacuation)
- abdominal bloating (more common in women than men), distension, tension or hardness
- symptoms made worse by eating
- passage of mucus.Other features such as lethargy, nausea, backache and bladder symptoms are common in people with IBS, and may be used to support the diagnosis. 
1.1.2 Diagnostic tests
184.108.40.206 In people who meet the IBS diagnostic criteria, the following tests should be undertaken to exclude other diagnoses:
- full blood count (FBC)
- erythrocyte sedimentation rate (ESR) or plasma viscosity
- c‑reactive protein (CRP)
- antibody testing for coeliac disease (endomysial antibodies [EMA] or tissue transglutaminase [TTG]). 
220.127.116.11 The following tests are not necessary to confirm diagnosis in people who meet the IBS diagnostic criteria:
- rigid/flexible sigmoidoscopy
- colonoscopy; barium enema
- thyroid function test
- faecal ova and parasite test
- faecal occult blood
- hydrogen breath test (for lactose intolerance and bacterial overgrowth). 
1.2 Clinical management of IBS
1.2.1 Dietary and lifestyle advice
18.104.22.168 People with IBS should be given information that explains the importance of self‑help in effectively managing their IBS. This should include information on general lifestyle, physical activity, diet and symptom‑targeted medication. 
22.214.171.124 Healthcare professionals should encourage people with IBS to identify and make the most of their available leisure time and to create relaxation time. 
126.96.36.199 Healthcare professionals should assess the physical activity levels of people with IBS, ideally using the General Practice Physical Activity Questionnaire (GPPAQ; see appendix J of the full guideline). People with low activity levels should be given brief advice and counselling to encourage them to increase their activity levels. 
188.8.131.52 Diet and nutrition should be assessed for people with IBS and the following general advice given.
- Have regular meals and take time to eat.
- Avoid missing meals or leaving long gaps between eating.
- Drink at least 8 cups of fluid per day, especially water or other non‑caffeinated drinks, for example herbal teas.
- Restrict tea and coffee to 3 cups per day.
- Reduce intake of alcohol and fizzy drinks.
- It may be helpful to limit intake of high‑fibre food (such as wholemeal or high‑fibre flour and breads, cereals high in bran, and whole grains such as brown rice).
- Reduce intake of ‘resistant starch’ (starch that resists digestion in the small intestine and reaches the colon intact), which is often found in processed or re‑cooked foods.
- Limit fresh fruit to 3 portions per day (a portion should be approximately 80 g).
- People with diarrhoea should avoid sorbitol, an artificial sweetener found in sugar‑free sweets (including chewing gum) and drinks, and in some diabetic and slimming products.
- People with wind and bloating may find it helpful to eat oats (such as oat‑based breakfast cereal or porridge) and linseeds (up to 1 tablespoon per day). 
184.108.40.206 Healthcare professionals should review the fibre intake of people with IBS, adjusting (usually reducing) it while monitoring the effect on symptoms. People with IBS should be discouraged from eating insoluble fibre (for example, bran). If an increase in dietary fibre is advised, it should be soluble fibre such as ispaghula powder or foods high in soluble fibre (for example, oats). 
220.127.116.11 People with IBS who choose to try probiotics should be advised to take the product for at least 4 weeks while monitoring the effect. Probiotics should be taken at the dose recommended by the manufacturer. 
18.104.22.168 Healthcare professionals should discourage the use of aloe vera in the treatment of IBS. 
22.214.171.124 If a person’s IBS symptoms persist while following general lifestyle and dietary advice, offer advice on further dietary management. Such advice should:
- include single food avoidance and exclusion diets (for example, a low FODMAP [fermentable oligosaccharides, disaccharides, monosaccharides and polyols] diet)
- only be given by a healthcare professional with expertise in dietary management. [new 2015]
1.2.2 Pharmacological therapy
Decisions about pharmacological management should be based on the nature and severity of symptoms. The recommendations made below assume that the choice of single or combination medication is determined by the predominant symptom(s).
126.96.36.199 Healthcare professionals should consider prescribing antispasmodic agents for people with IBS. These should be taken as required, alongside dietary and lifestyle advice. 
188.8.131.52 Laxatives should be considered for the treatment of constipation in people with IBS, but people should be discouraged from taking lactulose. 
184.108.40.206 Consider linaclotide for people with IBS only if:
- optimal or maximum tolerated doses of previous laxatives from different classes have not helped and
- they have had constipation for at least 12 months.Follow up people taking linaclotide after 3 months. [new 2015]
220.127.116.11 Loperamide should be the first choice of antimotility agent for diarrhoea in people with IBS. 
18.104.22.168People with IBS should be advised how to adjust their doses of laxative or antimotility agent according to the clinical response. The dose should be titrated according to stool consistency, with the aim of achieving a soft, well‑formed stool (corresponding to Bristol Stool Form Scale type 4). 
22.214.171.124 Consider tricyclic antidepressants (TCAs) as second‑line treatment for people with IBS if laxatives, loperamide or antispasmodics have not helped. Start treatment at a low dose (5–10 mg equivalent of amitriptyline), taken once at night, and review regularly. Increase the dose if needed, but not usually beyond 30 mg. 
126.96.36.199 Consider selective serotonin reuptake inhibitors (SSRIs) for people with IBS only if TCAs are ineffective.
188.8.131.52 Take into account the possible side effects when offering TCAs or SSRIs to people with IBS. Follow up people taking either of these drugs for the first time at low doses for the treatment of pain or discomfort in IBS after 4 weeks and then every 6–12 months.
1.2.3 Psychological interventions
184.108.40.206 Referral for psychological interventions (cognitive behavioural therapy [CBT], hypnotherapy and/or psychological therapy) should be considered for people with IBS who do not respond to pharmacological treatments after 12 months and who develop a continuing symptom profile (described as refractory IBS). 
1.2.4 Complementary and alternative medicine (CAM)
220.127.116.11 The use of acupuncture should not be encouraged for the treatment of IBS. 
18.104.22.168 The use of reflexology should not be encouraged for the treatment of IBS. 
22.214.171.124 Follow‑up should be agreed between the healthcare professional and the person with IBS, based on the response of the person’s symptoms to interventions. This should form part of the annual patient review. The emergence of any ‘red flag’ symptoms during management and follow‑up should prompt further investigation and/or referral to secondary care. 
To read the full guidelines click on the link given below.