Guidelines on Irritable Bowel Syndrome: Mechanisms and Practical Management Irritable bowel syndrome (IBS) affects 5–11% of the population in most countries, with prevalence peaking in the third and fourth decades of life, and a female predominance. These guidelines aim to provide a guide for the assessment and management of adult patients with IBS. The guidelines were developed by members of the Clinical Services Committee of the British Society of Gastroenterology, who conducted systematic literature searches using electronic databases and extensive personal reference databases. The guidelines are based on the best available evidence, with emphasis on randomized, placebo-controlled trials. The guidelines are designed for adults with IBS, though they are also likely to apply to most adolescents. The guidelines are aimed primarily at consultant gastroenterologists and trainees in gastroenterology, as well as general practitioners with a special interest in gastroenterology. A summary form of the document is available for use in primary care. IBS is a heterogeneous condition with a range of treatments, each of which benefits a small proportion of patients. Treatment of associated anxiety and depression often improves bowel and other symptoms. Randomized placebo-controlled trials show benefit as follows: cognitive behavioural therapy and psychodynamic interpersonal therapy improve coping; hypnotherapy benefits global symptoms in otherwise refractory patients; antispasmodics and tricyclic antidepressants improve pain; isapphula improves pain and bowel habit; 5-HT3 antagonists improve global symptoms, diarrhoea, and pain but may rarely cause unexplained colitis; 5-HT4 agonists improve global symptoms, constipation, and bloating; selective serotonin reuptake inhibitors improve global symptoms. The guidelines emphasize the importance of identifying which patients will respond to specific treatments. The guidelines also highlight the importance of considering the psychological aspects of IBS, as adverse psychological features and somatisation are often present. The guidelines also emphasize the importance of considering the cost-effectiveness of interventions and the barriers to their use in clinical practice. The guidelines also discuss the epidemiology of IBS, including the prevalence and incidence of the condition, the classification of IBS based on predominant bowel habit, and the natural history and prognosis of the condition. The guidelines also discuss the clinical features of IBS, including the symptoms, stool patterns, and associated non-gastrointestinal symptoms. The guidelines also discuss the mechanisms of IBS, including the role of genetics, gastrointestinal motility, visceral hypersensitivity, and the stress response. The guidelines also discuss the comorbidity of IBS with other diseases, including fibromyalgia, chronic fatigue syndrome, and temporomandibular joint disorder. The guidelines also discuss the importance of identifying alarm features that may warrant further investigation. The guidelines also discuss the importance of considering the psychological aspects of IBS, as adverse psychological features and somatisation are often present. The guidelines also discuss the importance of considering the cost-effectiveness of interventions and the barriersGuidelines on Irritable Bowel Syndrome: Mechanisms and Practical Management Irritable bowel syndrome (IBS) affects 5–11% of the population in most countries, with prevalence peaking in the third and fourth decades of life, and a female predominance. These guidelines aim to provide a guide for the assessment and management of adult patients with IBS. The guidelines were developed by members of the Clinical Services Committee of the British Society of Gastroenterology, who conducted systematic literature searches using electronic databases and extensive personal reference databases. The guidelines are based on the best available evidence, with emphasis on randomized, placebo-controlled trials. The guidelines are designed for adults with IBS, though they are also likely to apply to most adolescents. The guidelines are aimed primarily at consultant gastroenterologists and trainees in gastroenterology, as well as general practitioners with a special interest in gastroenterology. A summary form of the document is available for use in primary care. IBS is a heterogeneous condition with a range of treatments, each of which benefits a small proportion of patients. Treatment of associated anxiety and depression often improves bowel and other symptoms. Randomized placebo-controlled trials show benefit as follows: cognitive behavioural therapy and psychodynamic interpersonal therapy improve coping; hypnotherapy benefits global symptoms in otherwise refractory patients; antispasmodics and tricyclic antidepressants improve pain; isapphula improves pain and bowel habit; 5-HT3 antagonists improve global symptoms, diarrhoea, and pain but may rarely cause unexplained colitis; 5-HT4 agonists improve global symptoms, constipation, and bloating; selective serotonin reuptake inhibitors improve global symptoms. The guidelines emphasize the importance of identifying which patients will respond to specific treatments. The guidelines also highlight the importance of considering the psychological aspects of IBS, as adverse psychological features and somatisation are often present. The guidelines also emphasize the importance of considering the cost-effectiveness of interventions and the barriers to their use in clinical practice. The guidelines also discuss the epidemiology of IBS, including the prevalence and incidence of the condition, the classification of IBS based on predominant bowel habit, and the natural history and prognosis of the condition. The guidelines also discuss the clinical features of IBS, including the symptoms, stool patterns, and associated non-gastrointestinal symptoms. The guidelines also discuss the mechanisms of IBS, including the role of genetics, gastrointestinal motility, visceral hypersensitivity, and the stress response. The guidelines also discuss the comorbidity of IBS with other diseases, including fibromyalgia, chronic fatigue syndrome, and temporomandibular joint disorder. The guidelines also discuss the importance of identifying alarm features that may warrant further investigation. The guidelines also discuss the importance of considering the psychological aspects of IBS, as adverse psychological features and somatisation are often present. The guidelines also discuss the importance of considering the cost-effectiveness of interventions and the barriers