Irritable Bowel Syndrome (IBS): Symptoms, Causes & Treatment

Irritable bowel syndrome (IBS) is the most commonly diagnosed functional gastrointestinal disorder, affecting 10–15% of the global population and accounting for 25–50% of gastroenterology referrals. It is defined by Rome IV criteria: recurrent abdominal pain at least one day per week, associated with defecation, change in stool frequency, or change in stool appearance, persisting for at least three months. Crucially, structural, inflammatory, or biochemical abnormalities are absent on standard investigation.

Pathophysiology is multifactorial: visceral hypersensitivity (heightened pain perception from normal gut stimuli), dysregulated gut-brain axis signaling, altered gut motility, and intestinal microbiome imbalance all contribute. Post-infectious IBS — emerging after acute gastroenteritis — affects 10–25% of patients. Central sensitization, psychological comorbidities (anxiety, depression in ~50%), and early life adversity are strongly associated with symptom severity.

Although IBS causes no tissue damage and does not increase colorectal cancer risk, it profoundly impairs quality of life, productivity, and healthcare utilization. Management is multimodal: patient education, dietary modification (low-FODMAP diet, fiber adjustment), pharmacotherapy targeting the predominant symptom subtype, and psychological therapies including cognitive-behavioral therapy and gut-directed hypnotherapy.

• Recurrent abdominal pain or cramping relieved by defecation
• Bloating and excessive flatulence
• Diarrhea (IBS-D), constipation (IBS-C), or alternating pattern (IBS-M)
• Urgency, straining, and sensation of incomplete evacuation
• Mucus in stools (without blood)

• Visceral hypersensitivity: exaggerated pain perception from normal gut stimuli
• Gut-brain axis dysregulation involving serotonin signaling (90% of body serotonin is in the gut)
• Altered intestinal motility: too fast (IBS-D) or too slow (IBS-C)
• Gut microbiome dysbiosis: reduced microbial diversity
• Post-infectious IBS: following acute bacterial or viral gastroenteritis
• Psychological stress, anxiety, and early-life adversity sensitizing the gut-brain axis

• Female Gender: Women are 1.5-3 times more likely to develop IBS than men.
• Age: Most common between ages 20-50, but can occur at any age.
• Family History: Having family members with IBS increases your risk of developing the condition.
• Chronic Psychological Stress: Emotional stress, anxiety, and depression increase the likelihood of developing or exacerbating IBS.
• Poor Diet: Low fiber intake or excessive consumption of fatty and spicy foods is linked to increased symptoms.
• Sedentary Lifestyle: Lack of physical activity is associated with digestive problems.
• Smoking and Alcohol Use: Excessive smoking and alcohol consumption may worsen symptoms.
• Prior Gastrointestinal Infection: History of acute gastroenteritis increases the risk of developing IBS later.
• Mental Health Disorders: Depression, anxiety disorders, and other psychiatric conditions are associated with higher IBS rates.
• Certain Medications: Antibiotics and other medications may affect gut bacteria and increase symptoms.

Diagnosis is clinical using Rome IV criteria after excluding alarm features (rectal bleeding, unintentional weight loss, family history of colorectal cancer, nocturnal symptoms, age >50). Basic workup includes CBC, CRP/ESR, celiac serology, and stool culture. Colonoscopy is reserved for patients with alarm features or inadequate response to treatment.

Treatment is individualized by symptom subtype. Dietary modification: low-FODMAP diet reduces symptoms in 50–70% of patients; soluble fiber (psyllium) benefits IBS-C. Pharmacotherapy: antispasmodics (hyoscine, mebeverine) for pain/bloating; loperamide for IBS-D; osmotic laxatives or linaclotide for IBS-C; low-dose TCAs or SSRIs modulate visceral sensitivity. Rifaximin (IBS-D) reduces bloating via microbiome modulation. Psychological therapies (CBT, gut-directed hypnotherapy) are effective especially when psychological comorbidities coexist.

• Significant reduction in quality of life and work productivity
• Comorbid anxiety and depression worsening the disease course
• Healthcare overutilization and invasive investigations due to diagnostic uncertainty

• Stress management through mindfulness, yoga, and regular exercise reduces flare frequency
• Identify and avoid personal dietary triggers (common: lactose, wheat, high-FODMAP foods)
• Maintain consistent sleep schedules and regular physical activity