Irritable Bowel Syndrom

Gastrointestinal

Description

Irritable bowel syndrome is a chronic functional gastrointestinal disorder defined by recurrent abdominal pain associated with altered bowel habits—diarrhoea, constipation, or a fluctuating pattern of both—in the absence of detectable structural or biochemical abnormalities. The Rome IV criteria require at least one day per week of abdominal pain on average during the previous three months, beginning at least six months before diagnosis, and related to defecation or associated with a change in stool frequency or form. Four subtypes are recognised according to predominant stool pattern: IBS with constipation (IBS-C), IBS with diarrhoea (IBS-D), mixed IBS (IBS-M), and unclassified IBS. Worldwide prevalence averages 5 %–10 %, with considerable impact on quality of life and health-care utilisation.

Symptoms

Cardinal complaints include crampy or aching abdominal pain that improves or worsens after defecation, bloating and abdominal distension, excessive flatulence, stool urgency or sensation of incomplete evacuation, and passage of mucus. IBS-C produces hard or lumpy stools and infrequent bowel movements, whereas IBS-D manifests loose or watery stools often precipitated by meals. Extra-intestinal symptoms—fatigue, headache, back pain, urinary frequency, and dyspareunia—are common. Weight loss, nocturnal diarrhoea, rectal bleeding, anaemia, or fever are atypical and suggest organic disease.

Risk Factors

Female sex, age below 50, family clustering, history of childhood sexual or physical abuse, mood and anxiety disorders, somatic pain syndromes such as fibromyalgia and chronic pelvic pain, acute infectious gastroenteritis, long-term antibiotic or proton-pump-inhibitor use, low-fibre or highly processed diets, sleep disturbance, sedentary lifestyle, and shift-work circadian disruption increase the likelihood of developing IBS.

Diagnosis

A positive diagnosis is made by applying Rome IV symptom criteria in conjunction with a normal physical examination and limited laboratory testing: complete blood count, C-reactive protein or erythrocyte-sedimentation rate, and coeliac serology. In IBS-D, faecal calprotectin excludes inflammatory bowel disease and a seven-day 75-SeHCAT scan or serum C4 detects bile-acid malabsorption when diarrhoea persists despite therapy. Age-appropriate colonoscopy screens for colorectal cancer in patients aged 45 or with alarm features. Breath testing for lactose malabsorption or small-intestinal bacterial overgrowth (SIBO) is reserved for refractory bloating. Routine abdominal imaging or extensive stool microbiology is unnecessary in typical presentations.

Treatment

Management follows a step-wise, subtype-tailored approach centred on patient education, dietary modification, psychological therapy, and pharmacologic agents. First-line measures include a trial of soluble-fibre supplementation with psyllium 5–10 g daily and reduction of caffeine, alcohol, fat, and gas-producing vegetables. A four- to six-week low-FODMAP diet supervised by a dietitian improves global symptoms in 60 %–70 % of patients, followed by structured reintroduction to identify triggers. Peppermint-oil capsules 180 mg three times daily alleviate post-prandial pain via calcium-channel blockade of enteric smooth muscle. For IBS-C, osmotic laxatives such as polyethylene-glycol, fibre, or magnesium hydroxide increase stool frequency. Prescription agents include chloride-channel activator lubiprostone 8 µg twice daily, guanylate-cyclase C agonists linaclotide 290 µg once daily or plecanatide 3 mg once daily, and the selective 5-HT4 agonist prucalopride 2 mg once daily. For IBS-D, loperamide controls urgency and frequency, while bile-acid sequestrants (cholestyramine, colesevelam) benefit patients with bile-acid diarrhoea. The rifaximin 550 mg three-times-daily course for fourteen days reduces bloating and loose stools and can be repeated twice for relapse. Mixed μ-opioid agonist and δ-antagonist eluxadoline 100 mg twice daily diminishes stool frequency and pain but is contraindicated in pancreatitis or prior cholecystectomy. Low-dose tricyclic antidepressants (amitriptyline or nortriptyline 10–25 mg at night) and selective serotonin re-uptake inhibitors (escitalopram, sertraline) modulate pain amplification and bowel function across subtypes. Second-line non-pharmacologic therapies include cognitive-behavioural therapy, gut-directed hypnotherapy, and mindfulness-based stress reduction, producing durable symptom relief comparable to medications. Regular exercise of moderate intensity (150 minutes weekly) improves bowel transit and mood.

Outlook

About half of patients experience persistent but fluctuating symptoms over years; one-third improve substantially with multifaceted therapy; fewer than 10 % develop progressively severe disability. Quality-of-life burden rivals chronic renal failure or diabetes but declines with effective coping strategies. IBS does not predispose to inflammatory bowel disease or colorectal cancer.

Complications

IBS itself does not harm the bowel, but chronic pain and unpredictability can lead to depression, anxiety, absenteeism, social withdrawal, disordered eating, financial burdens, and overuse of opioids or unnecessary surgeries. Severe IBS-D contributes to dehydration and electrolyte imbalance; severe IBS-C can precipitate faecal impaction.

Prevention

Early treatment of acute gastroenteritis, prudent use of antibiotics, regular physical activity, and resilience training against psychological stress may lower IBS incidence. Gradual increases in dietary fibre and mindful eating habits in childhood create a protective gut environment.

Support

Keep a detailed food and symptom diary to identify personal triggers; eat regular, unhurried meals and avoid skipping breakfast; limit FODMAP-rich foods such as onions, garlic, honey, legumes, wheat, apples, and certain milk products; sip fluids rather than gulping carbonated drinks; practise diaphragmatic breathing or progressive muscle relaxation ten minutes daily; and incorporate brisk walking or yoga into routine. Family members can facilitate by preparing IBS-friendly meals, encouraging stress-management activities, and supporting clinic visits.