Irritable Bowel Syndrome

Irritable bowel syndrome is a chronic disorder of gut brain interaction that causes recurrent abdominal pain and altered bowel habit. Routine tests do not show destructive bowel disease, but the altered movement, sensation and signalling are real. Diagnosis uses a characteristic symptom pattern, a focused examination and a limited set of tests while checking carefully for alarm features.

What irritable bowel syndrome is Irritable bowel syndrome is usually shortened to IBS. It is a chronic disorder of gut brain interaction involving recurrent abdominal pain and altered bowel habit. The bowel can look structurally normal on routine tests while its movement, sensitivity and signalling behave differently. IBS is therefore a real functional disorder rather than imaginary symptoms or hidden tissue damage assumed without evidence. Functional does not mean nothing is wrong In medicine, functional describes altered operation rather than visible structural destruction. The bowel can contract differently, sense stretching more intensely and communicate with the nervous system in an altered way. These changes can produce substantial pain, urgency, constipation, diarrhoea and bloating. A normal scan or colonoscopy does not make those effects unreal. Disorder of gut brain interaction Modern specialist guidance describes IBS as a disorder of gut brain interaction. The gut and brain communicate continuously through nerves, hormones, immune signals and learned responses. This communication influences movement, secretion, sensitivity and attention to internal sensations. IBS can involve changes at several points within this network rather than one damaged organ. The gut brain axis The gut brain axis is the two way communication system linking the digestive tract and central nervous system. Signals travel upwards from the bowel and downwards from the brain. Meals, sleep, infection, stress and emotion can alter these signals. This does not mean that stress is the sole cause or that symptoms are under voluntary control. Visceral hypersensitivity Visceral hypersensitivity means that internal bowel sensations are felt more intensely than expected. Normal amounts of gas or stretching can become painful or urgent. The bowel is not necessarily more damaged when the pain is stronger. Sensitivity can vary from day to day and between different bowel regions. Altered bowel movement The muscles and nerves of the bowel coordinate movement of fluid, gas and stool. Transit can become faster, slower or less coordinated in IBS. Faster transit can contribute to loose stool and urgency. Slower transit or impaired evacuation can contribute to constipation and incomplete emptying. More than one mechanism can coexist IBS does not have one universal biological cause. A person may have visceral hypersensitivity, altered movement and a response to particular fermentable carbohydrates. Another may develop symptoms after infection or alongside pelvic floor difficulty. The treatment plan therefore targets the person's dominant symptoms and contributors. IBS after gastroenteritis Some people develop IBS after an episode of infectious gastroenteritis. This is called post infectious IBS. Persistent changes in immune activity, gut bacteria, nerve sensitivity and barrier function may contribute. The original infection has usually cleared, so repeated antibiotics do not treat the later IBS pattern. Gut microorganisms The colon contains a large community of bacteria and other microorganisms. They ferment carbohydrates that are not absorbed in the small intestine. This produces gases and other compounds that can influence bowel movement and sensation. No single microbiome test currently diagnoses ordinary IBS or selects a guaranteed treatment. IBS is not inflammatory bowel disease Inflammatory bowel disease is usually shortened to IBD. Crohn's disease and ulcerative colitis cause measurable inflammation and can damage bowel tissue. IBS does not cause the same ulceration, bleeding or inflammatory injury. The symptom patterns can overlap, so tests are used when IBD remains possible. IBS is not coeliac disease Coeliac disease is an immune reaction to gluten that damages the small intestinal lining in susceptible people. It can cause diarrhoea, bloating, pain, anaemia and weight loss. Adults being assessed for IBS should receive coeliac serology while still eating gluten. A gluten free diet started before testing can make the result falsely reassuring. IBS is not bowel cancer IBS itself does not develop into bowel cancer and does not increase cancer risk in the way inflammatory bowel disease can. However, cancer can initially produce bowel symptoms that resemble IBS. New alarm features or a major change in the established pattern require reassessment rather than automatic attribution to IBS. IBS does not shorten life IBS is not generally life shortening and does not progressively destroy the bowel. It can still be disabling through pain, urgency, disrupted sleep, restricted eating and fear of leaving home. Clinical care should avoid alarming over investigation while taking the effect on quality of life seriously. The central symptom pattern Recurrent abdominal pain is central to modern IBS definitions. The pain is related to defecation, a change in stool frequency or a change in stool form. It may improve after a bowel movement, worsen afterwards or simply occur around the same time. Pain that never relates to bowel function may suggest another diagnosis. Rome IV style criteria Rome IV criteria require recurrent abdominal pain on average at least one day each week during the last three months. The pain is associated with at least two features involving defecation, stool frequency or stool form. Symptoms should have started at least six months before diagnosis. These criteria create consistency, especially in research, but clinicians interpret the whole presentation. NICE symptom duration NICE advises considering IBS assessment when abdominal pain or discomfort, bloating or altered bowel habit has been present for at least six months. This duration helps separate a chronic pattern from one brief infection or temporary dietary change. It should not delay investigation when alarm features are present. NICE diagnostic symptom pattern NICE considers IBS when abdominal pain or discomfort is relieved by defecation or associated with altered stool frequency or form. At least two supporting features should accompany this pattern. These include altered stool passage, bloating, symptoms worsened by eating and passage of mucus. Altered stool passage Altered passage includes straining, urgency and a feeling of incomplete evacuation. Some people need repeated bowel movements before feeling empty. Others experience sudden urgency despite passing a small amount. These symptoms can also occur with pelvic floor disorders and other bowel conditions. Bloating and distension Bloating is the sensation of pressure, fullness or swelling. Distension is a visible increase in abdominal size. The two can occur together or separately. Gas volume, bowel contents, abdominal wall responses and visceral sensitivity can all contribute. Symptoms after eating Meals activate normal bowel movement through the gastrocolic response. This response can feel exaggerated in IBS and trigger pain, urgency or bloating. Symptoms after food do not prove a food allergy or intolerance. Restricting several foods without a structured plan can create nutritional problems. Mucus Clear or whitish mucus can appear with stool in IBS. The bowel normally produces mucus to lubricate stool. Visible mucus without blood can support the symptom pattern but is not specific. Blood mixed with stool or persistent rectal bleeding requires another assessment pathway. Pain location IBS pain can occur anywhere in the abdomen and may move between sites. Lower abdominal pain is common, but upper abdominal discomfort can occur. A fixed progressive pain, localised tenderness or palpable mass is less typical and needs review. Pain severity Pain severity varies widely and does not measure structural damage. Some people experience short cramps around bowel movements. Others have prolonged pain that disrupts work and sleep. Severe pain still deserves assessment because IBS should not be used to dismiss a new emergency. Diarrhoea symptoms IBS related diarrhoea can involve loose stool, urgency and frequent bowel movements. Some people pass several stools in the morning and then settle later. Faecal incontinence can occur and should be asked about directly and sensitively. Persistent watery diarrhoea during sleep is less typical and requires further assessment. Constipation symptoms Constipation can involve hard stool, infrequent bowel movements or difficult evacuation. A person may strain, feel blocked or need several attempts. Frequency alone does not describe the full problem. Medicines, pelvic floor dysfunction and metabolic conditions can cause similar symptoms. Alternating bowel habit Some people alternate between hard and loose stools. A loose stool after several days of constipation can reflect overflow around retained stool rather than a true switch to diarrhoea. The Bristol Stool Form Scale and a symptom diary can clarify the pattern. Bristol Stool Form Scale The Bristol Stool Form Scale groups stool appearance from type 1 to type 7. Types 1 and 2 are hard or lumpy. Types 3 and 4 are more formed, while types 6 and 7 are loose or watery. The scale describes appearance and does not diagnose the cause. IBS subtypes IBS subtypes are based mainly on stool form during abnormal bowel movements. They help select treatment but are not separate diseases. A person's subtype can change over time. Reassessment is more useful than assuming one label remains permanent. IBS with constipation IBS with constipation is shortened to IBS C. Hard or lumpy stools predominate, while loose or watery stools are uncommon without laxatives. Pain remains necessary for the IBS diagnosis. Constipation without recurrent abdominal pain may fit a different functional bowel disorder. IBS with diarrhoea IBS with diarrhoea is shortened to IBS D. Loose or watery stools predominate, while hard stools are uncommon without antidiarrhoeal treatment. Urgency and fear of accidents can have a major social impact. Ongoing watery diarrhoea requires consideration of IBD, bile acid diarrhoea, coeliac disease and infection. Mixed IBS Mixed IBS is shortened to IBS M. Both hard or lumpy stools and loose or watery stools occur often enough to define the pattern. Treatment may need to change according to the current dominant symptom. Taking a laxative and an antimotility medicine without a plan can make fluctuation harder to interpret. Unclassified IBS Unclassified IBS is shortened to IBS U. The person meets the pain based IBS criteria but the abnormal stool pattern does not fit the other subtypes. It does not mean that the diagnosis is uncertain or less genuine. Symptoms outside the bowel Fatigue, nausea, backache and bladder symptoms can accompany IBS. Headache, pelvic pain and sleep disturbance are also reported more often. These features may reflect shared sensitivity and nervous system pathways. They are non specific and should not be attributed automatically to IBS. Menstrual and pelvic symptoms Bowel symptoms can change around menstruation because hormones affect pain and movement. Endometriosis, ovarian disease and pelvic floor conditions can resemble IBS. Pain linked strongly to menstruation, painful sex or fertility concerns requires a broader assessment. IBS and mental health Anxiety and depression are more common among people with severe IBS. This does not prove that psychological distress caused the bowel disorder. Symptoms can create anxiety, while stress and threat responses can amplify gut signalling. Both physical and psychological needs deserve appropriate care. Quality of life effects Unpredictable urgency can restrict travel, work, education and relationships. Pain and bloating can alter clothing choices and confidence. Food fear can lead to increasingly narrow diets. The absence of life shortening tissue disease does not make these effects trivial. A positive diagnosis rather than endless exclusion IBS is sometimes described as a diagnosis of exclusion. Modern practice aims to make a positive diagnosis from the characteristic pattern after checking for alarm features and common alternatives. A limited test panel is usually sufficient when the presentation fits. Endless normal investigations can reinforce fear without improving symptoms. Clinical assessment The clinician asks about pain, stool form, frequency, urgency and incomplete evacuation. They establish duration, change over time and the effect on daily life. They review medicines, diet, travel, infection, health problems in the family and menstrual or pelvic symptoms where relevant. Physical examination The clinician assesses general health and examines the abdomen. They look for pallor, weight loss, fever, tenderness and a mass. A rectal examination may be appropriate when bleeding, evacuation difficulty or a mass is a concern. A normal examination supports reassurance but does not by itself confirm IBS. Alarm features change the pathway Alarm features do not prove cancer or inflammatory disease. They increase the need for further investigation or referral rather than a routine IBS diagnosis. The exact pathway depends on age, symptom combination, examination and current NICE guidance. Rectal bleeding IBS does not cause rectal bleeding. Common benign causes include haemorrhoids and anal fissures, but bleeding still needs assessment. Current colorectal pathways may include a faecal immunochemical test and referral based on the full pattern. A rectal mass can require direct suspected cancer referral. Unintentional weight loss Weight loss that was not planned is not a routine IBS feature. It can result from reduced intake, malabsorption, inflammation or cancer. Self restriction because eating triggers symptoms can also cause weight loss and requires support. Anaemia Iron deficiency anaemia can result from bleeding or impaired nutrient absorption. IBS itself does not cause anaemia. A full blood count identifies an anaemia pattern but does not establish the cause. Unexplained anaemia requires investigation according to age and clinical context. Nocturnal symptoms IBS symptoms can occasionally disturb sleep, particularly during a flare. Repeated nocturnal diarrhoea or symptoms consistently waking someone from sleep are less typical. They raise concern for inflammation, microscopic colitis, infection or another organic condition. New onset after age 50 IBS can exist in older adults, but a first presentation after age 50 needs careful assessment. Age changes the probability of colorectal and other diseases and affects cancer testing pathways. The person should not be reassured solely because the symptoms resemble a previous description of IBS. Ovarian cancer consideration NICE advises ovarian cancer testing when a woman or another person with female reproductive organs aged 50 or over develops new IBS type symptoms within the previous year. IBS rarely presents for the first time at that age in this group. Persistent bloating, early fullness, pelvic pain or urinary urgency also need appropriate assessment. Family history A strong colorectal in the family, ovarian or related cancers can change risk and investigation thresholds. The clinician asks which relative was affected and at what age. A vague health problems in the family should be clarified rather than ignored or treated as proof of inherited cancer. Abdominal or rectal mass A palpable abdominal or rectal mass is not explained by IBS. It requires prompt investigation and can trigger a suspected cancer pathway. Persistent localised swelling should not be labelled as ordinary bloating without examination. Fever and inflammatory signs Persistent fever is not a typical IBS feature. Raised CRP, ESR or plasma viscosity can suggest inflammatory disease but are not specific. Normal inflammatory markers reduce the probability of active IBD but do not exclude every form. First line blood tests NICE recommends a full blood count, inflammatory markers and coeliac serology when the symptom pattern fits IBS. Inflammatory testing includes CRP and ESR or plasma viscosity according to the local laboratory pathway. These tests look for anaemia, inflammation and coeliac disease rather than proving IBS directly. Full blood count A full blood count measures haemoglobin, red cells, white cells and platelets. Anaemia or thrombocytosis can change the investigation pathway. A normal result supports a lower risk picture but does not rule out every bowel disease. CRP and ESR C reactive protein is shortened to CRP. Erythrocyte sedimentation rate is shortened to ESR. Both can rise during inflammation but can also change for unrelated reasons. They are probability markers rather than diagnoses. Coeliac serology The usual first blood tests include total IgA and IgA tissue transglutaminase antibodies. Testing is accurate only when the person is eating enough gluten. A positive blood result usually leads to specialist confirmation rather than an immediate lifelong diet started alone. Faecal calprotectin Faecal calprotectin measures a protein released mainly by inflammatory white cells within the bowel. NICE recommends it as an option when distinguishing IBD from IBS in adults with recent lower gastrointestinal symptoms. It is used when cancer is not suspected and local quality assured pathways are available. What calprotectin can and cannot show A low result makes active IBD less likely in the appropriate setting. A raised result does not prove Crohn's disease or ulcerative colitis. Infection, NSAID use and other bowel inflammation can increase it. The result requires interpretation with symptoms, age and local thresholds. FIT and calprotectin are different A faecal immunochemical test is usually shortened to FIT. FIT detects small amounts of human blood and guides colorectal cancer referral in selected symptomatic adults. Calprotectin estimates intestinal inflammation and helps distinguish IBD from non inflammatory disorders. Neither test replaces clinical assessment or can be substituted automatically for the other. Tests not routinely required When the symptom pattern fits, red flags are absent and initial tests are reassuring, routine colonoscopy is not needed to confirm IBS. NICE also does not require routine ultrasound, thyroid testing, parasite testing or hydrogen breath testing for every case. Targeted tests remain appropriate when what the person describes suggests a specific alternative. Why avoiding unnecessary colonoscopy matters Colonoscopy is valuable when inflammation, cancer or another structural disorder is possible. It requires bowel preparation and carries small risks including bleeding and perforation. Using it routinely for a low risk positive IBS diagnosis can cause harm and delay symptom focused care. Diagnosis can be reviewed A diagnosis is not a promise that no future disease can occur. New bleeding, weight loss, anaemia or a major pattern change requires reassessment. Long standing IBS should not be used to explain every later abdominal symptom automatically. Treatment goals IBS treatment aims to reduce symptoms and improve daily function. There is no single cure that works for everyone. The person and clinician identify the most disruptive symptoms and choose a stepwise plan. Success can mean fewer severe days rather than complete absence of all sensations. Explanation is part of treatment A clear positive diagnosis can reduce fear and repeated emergency searching. The explanation should confirm that symptoms are real and describe the gut brain mechanisms simply. It should also identify the specific features that require future reassessment. Reassurance without explanation can feel dismissive. Avoid over medicalising normal variation Bowel frequency and stool form vary between healthy people. One episode of bloating or loose stool does not establish a chronic syndrome. Treatment should match the level of disruption rather than turning every bowel sensation into disease monitoring. Regular meals NICE advises regular meals and avoiding long gaps where possible. Eating slowly can reduce swallowed air and help the person observe portion effects. Rigid eating rules can worsen anxiety and should not replace individual assessment. Fluid and caffeine Adequate fluid supports stool consistency, especially when soluble fibre is increased. High caffeine intake can worsen urgency and loose stool in some people. NICE advises limiting tea and coffee and reducing fizzy drinks and excess alcohol. Individual response matters more than a universal prohibition. Food triggers Some people identify reproducible triggers such as large fatty meals, onions or particular sweeteners. A symptom diary can test one change at a time. A long list based on one difficult day can lead to unnecessary restriction. True food allergy usually has a different pattern and requires separate assessment. Fibre is not one substance Dietary fibre includes several compounds with different effects on water, fermentation and stool bulk. Advice to simply eat more fibre can worsen IBS symptoms. The type, amount and rate of increase matter. Soluble fibre Soluble fibre absorbs water and can form a gel. Examples include ispaghula husk, oats and linseeds. It can soften hard stool and sometimes improve overall IBS symptoms. The amount is increased gradually with adequate fluid to reduce bloating. Insoluble fibre Insoluble fibre adds coarse bulk and passes through the bowel less fermented. Wheat bran is a common example. NICE advises discouraging bran in IBS because it can worsen pain, bloating and urgency. This differs from general population advice about whole grains. Resistant starch and sorbitol Resistant starch reaches the colon without complete small intestinal digestion and can be fermented. Reheated processed starches can be important for some people. Sorbitol in sugar free sweets, gum and drinks can draw water into the bowel and worsen diarrhoea. These are possible triggers rather than universal toxins. The low FODMAP approach FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These short chain carbohydrates can draw water into the bowel and undergo rapid fermentation. A low FODMAP approach can reduce pain, bloating and altered bowel habit in some people. It is not necessary or effective for everyone. Low FODMAP is a structured process The first phase temporarily reduces high FODMAP foods. Foods are then reintroduced systematically to identify tolerated groups and amounts. The final phase creates the broadest personalised diet that controls symptoms reasonably. It should not become permanent blanket avoidance of many food groups. Dietitian support NICE states that exclusion diets such as low FODMAP should be guided by a professional with dietary expertise. A dietitian checks nutritional adequacy, weight, eating patterns and practical access to food. Support is particularly important during pregnancy, frailty, diabetes, eating disorder risk or an already restricted diet. Risks of prolonged restriction A highly restrictive diet can reduce fibre, calcium and other nutrients. It can affect the gut microbial community and make eating socially difficult. Fear driven restriction can also reinforce symptoms and weight loss. Reintroduction is therefore an essential treatment phase rather than a failed diet. Physical activity Regular activity can support bowel movement, sleep and general wellbeing. People with low activity levels can increase gradually according to fitness and other health conditions. Exercise should not be presented as proof that symptoms are caused by inactivity. Sleep and routine Poor sleep can increase pain sensitivity and fatigue. Shift work can disrupt meals and bowel timing. A realistic routine can reduce some variability without controlling every flare. Antispasmodic medicines Antispasmodics reduce contraction or spasm within bowel muscle and can help episodic cramping. NICE considers them as required alongside lifestyle and dietary care. Different products have different contraindications and adverse effects. They should not be started casually when severe new pain or obstruction is possible. Peppermint oil Enteric coated peppermint oil has an antispasmodic effect and can help some people. It can worsen reflux and cause anal burning or other adverse effects. A pharmacist or prescriber can check suitability and interactions. Laxatives for IBS C Laxatives can be considered when constipation remains troublesome. The choice depends on stool form, hydration, medicines and evacuation symptoms. NICE discourages lactulose in IBS because fermentation can worsen gas and bloating. Dose adjustment aims for a soft formed stool rather than diarrhoea. More persistent IBS C Linaclotide can be considered when constipation has lasted at least twelve months and several laxative classes have not helped at tolerated doses. It is not a first casual treatment for occasional constipation. Clinical follow up checks benefit and diarrhoea related adverse effects. Loperamide for IBS D NICE identifies loperamide as the first choice antimotility medicine for diarrhoea in IBS. It slows bowel transit and can reduce urgency and stool frequency. The dose is adjusted to clinical response under professional or pharmacy advice. It treats the symptom pattern rather than the underlying gut brain mechanisms. When not to self treat diarrhoea Loperamide should not be used to hide bloody diarrhoea, fever or severe abdominal distension. Suspected infection, inflammatory colitis or bowel obstruction requires assessment. Persistent diarrhoea with weight loss, anaemia or night time symptoms needs investigation rather than repeated suppression. Combining bowel medicines Some people need different treatments during different symptom phases. A written plan can explain when to reduce or pause a medicine. Unplanned cycling between laxatives and loperamide can intensify stool variability. Low dose tricyclic medicines NICE considers a tricyclic antidepressant as second line treatment when antispasmodics, laxatives or loperamide have not helped. The dose used for IBS pain is usually much lower than a dose used to treat depression. The medicine acts as a gut directed neuromodulator by changing pain signalling and bowel function. Its use does not imply that symptoms are imagined or that the person has depression. Tricyclic safety These medicines can cause dry mouth, constipation, blurred vision, drowsiness and difficulty passing urine. They can affect heart rhythm and may be unsuitable with particular cardiac, eye or prostate conditions. NICE recommends starting low, reviewing after four weeks and continuing periodic review. This is an off label use requiring informed prescribing. Selective serotonin reuptake inhibitors NICE considers an SSRI only when a tricyclic is ineffective in the IBS pathway. The balance can differ when a separate anxiety or depressive disorder needs treatment. SSRIs can initially worsen nausea or diarrhoea in some people. Probiotics People who choose to try a probiotic can use one product at the manufacturer's recommended dose for at least four weeks while monitoring symptoms. Products contain different strains and doses, so benefit from one cannot be assumed for another. They should be stopped if no clear benefit appears. Psychological therapies are gut treatments Psychological therapies can change the way the brain processes gut sensations and threat. They can also reduce avoidance, symptom monitoring and stress related amplification. Offering them does not mean that IBS is invented or caused by weak coping. Cognitive behavioural therapy IBS focused cognitive behavioural therapy is usually shortened to CBT. It explores thoughts, behaviours and physiological responses that maintain distress or disability. Examples include fear of eating, avoidance of travel and constant checking for bowel sensations. CBT aims to improve function and symptom coping rather than persuade someone that pain is unreal. Gut directed hypnotherapy Gut directed hypnotherapy uses focused relaxation and therapeutic suggestions aimed at gut sensation and function. It is delivered by a trained practitioner through a structured course. It differs from entertainment hypnosis and does not remove personal control. When psychological therapy is considered NICE advises considering CBT, hypnotherapy or psychological therapy when symptoms remain refractory after twelve months of drug treatment. Specialist guidance also supports earlier access where available and aligned with the person's preference. The diagnosis should be reviewed when symptoms are severe or treatment resistant. Stress management Relaxation, mindfulness and pacing can help some people regulate arousal and cope with flares. They are supportive strategies rather than proof that stress caused IBS. Workplace, financial or caring pressures may need practical support rather than only relaxation advice. Pelvic floor assessment Some people with constipation have difficulty coordinating the pelvic floor muscles during defecation. Clues include prolonged straining, blockage sensation and manual assistance. Targeted anorectal testing and biofeedback may be more appropriate than escalating laxatives indefinitely. Specialist referral Referral is appropriate when alarm features appear, tests are abnormal or the diagnosis remains uncertain. Severe refractory symptoms, major dietary restriction or possible pelvic floor dysfunction can also justify specialist care. Referral should have a clear question rather than imply that every person needs colonoscopy. Follow up Follow up is based on symptom response and the treatment plan. NICE advises reviewing for newly developed red flags. Regular review also prevents unnecessary long term restriction and medicine use. Flares and remission IBS commonly fluctuates. A flare can follow infection, travel, disrupted sleep, menstrual change or a stressful period. Sometimes no trigger is identifiable. A flare does not automatically mean the bowel is being damaged. Reassessing a changed pattern A major sustained change in pain, stool or general health deserves review. Ageing, new medicines and unrelated bowel disease can alter symptoms. The previous IBS diagnosis remains relevant but should not close future clinical reasoning. Living well without minimising the condition The aim is not to monitor every meal and bowel movement indefinitely. A practical plan can identify a small number of effective strategies and clear safety netting. The condition is chronic but often manageable, and many people experience long periods of improvement. What this lesson should not be used for This lesson cannot diagnose IBS from bloating, pain or stool appearance alone. Do not use a low calprotectin result or normal blood test as proof that every future symptom is harmless. Do not begin a highly restrictive diet or several bowel medicines without appropriate advice. Do not label rectal bleeding, weight loss, anaemia or a mass as IBS. Call 999 for severe acute abdominal pain with collapse, major bleeding or another medical emergency.

IBS is a real disorder of gut brain interaction that changes bowel sensation, movement and signalling without causing the destructive inflammation seen in IBD. A positive diagnosis uses a characteristic pain and bowel habit pattern, focused examination and limited tests, while alarm features require a different pathway. Treatment is individualised by symptoms and should protect nutrition, function and quality of life.