Irritable Bowel Syndrome (IBS) is a common, chronic functional gastrointestinal disorder that affects the large intestine (colon). It is characterized by a group of symptoms that occur together, including abdominal pain or discomfort and changes in bowel habits, without evidence of structural or biochemical abnormalities.

Key Features of IBS:

• Abdominal pain or discomfort that is often relieved by defecation.
• Altered bowel habits: diarrhea, constipation, or a mix of both.
• Bloating and gas.
• Mucus in the stool (common but not universal).
• Symptoms typically persist for at least 3 months, with onset at least 6 months before diagnosis.

Subtypes of IBS:

IBS is classified based on the predominant stool pattern:

1. IBS with constipation (IBS-C) – hard or lumpy stools ≥25% of the time; loose stools <25%.
2. IBS with diarrhea (IBS-D) – loose or watery stools ≥25% of the time; hard stools <25%.
3. Mixed IBS (IBS-M) – both hard and loose stools ≥25% of the time.
4. Unsubtyped IBS (IBS-U) – doesn’t meet criteria for the above subtypes.

Diagnostic Criteria (Rome IV Criteria):

To be diagnosed with IBS, a person must have recurrent abdominal pain, on average, at least 1 day per week in the last 3 months, associated with two or more of the following:

• Related to defecation
• Associated with a change in the frequency of stool
• Associated with a change in the form (appearance) of stool

Symptoms must have started at least 6 months prior.

Possible Causes & Triggers:

The exact cause is unknown, but contributing factors may include:

• Gut-brain axis dysfunction: Altered communication between the brain and gut.
• Visceral hypersensitivity: Increased sensitivity to pain in the intestines.
• Altered gut motility: Abnormal contractions of intestinal muscles.
• Gut microbiota imbalance: Changes in the composition of gut bacteria.
• Post-infectious IBS: Can develop after a gastrointestinal infection.
• Food intolerances: Especially to FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols).
• Stress and psychological factors: Anxiety, depression, or trauma can worsen symptoms.
• Hormonal changes: More common in women, often worsening around menstruation.

Management & Treatment:

There is no cure for IBS, but symptoms can often be managed effectively:

1. Dietary Modifications:

• Low-FODMAP diet: Shown to reduce symptoms in many patients (should be guided by a dietitian).
• Increase soluble fiber (e.g., psyllium) for IBS-C; avoid insoluble fiber if it worsens bloating.
• Stay hydrated and eat regular meals.
• Limit caffeine, alcohol, and fatty foods.

2. Lifestyle Changes:

• Stress management (e.g., cognitive behavioral therapy, mindfulness, yoga).
• Regular physical activity.
• Adequate sleep.

3. Medications (based on subtype):

• IBS-C: Linaclotide, lubiprostone, or osmotic laxatives (e.g., polyethylene glycol).
• IBS-D: Loperamide (for diarrhea), eluxadoline, or bile acid sequestrants.
• Pain/bloating: Antispasmodics (e.g., hyoscine, dicyclomine).
• Antidepressants: Low-dose tricyclic antidepressants (TCAs) or SSRIs may help with pain and mood.
• Rifaximin: An antibiotic that may help in IBS-D by modulating gut bacteria.

4. Psychological Therapies:

• Cognitive behavioral therapy (CBT), gut-directed hypnotherapy, and mindfulness-based stress reduction have strong evidence for improving IBS symptoms.

When to See a Doctor:

Seek medical evaluation if you experience alarm symptoms, which may suggest a different condition (e.g., inflammatory bowel disease or cancer):

• Unintended weight loss
• Rectal bleeding or black/tarry stools
• Persistent vomiting
• Fever
• Family history of colorectal cancer or IBD
• Onset after age 50

Prognosis:

IBS is not life-threatening and does not increase the risk of colorectal cancer. While chronic, many people achieve good symptom control with lifestyle, dietary, and medical interventions.