Irritable Bowel Syndrome (IBS)

What is Irritable Bowel Syndrome (IBS)?

Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder affecting the stomach and small intestines. It causes abdominal pain and changes in bowel movements—diarrhea, constipation, or alternating between the two. The exact cause is not fully understood but involves factors such as:

  • Brain–gut interaction problems
  • Abnormal gut motility
  • Infections (post-infectious IBS)
  • Stress and psychological factors
  • Genetics

IBS does not damage digestive tissues or increase cancer risk. Subtypes based on the predominant bowel habit include:

  • IBS with constipation (IBS-C)
  • IBS with diarrhea (IBS-D)
  • Mixed IBS (IBS-M, both constipation and diarrhea)

Diagnosis involves ruling out other conditions via medical history, physical exam, and tests. Treatment focuses on symptom management through diet, lifestyle, medications, and psychological therapies.

What causes irritable bowel syndrome?

The causes of IBS are multifactorial:

  • Brain–gut interaction: Abnormal signaling causes altered motility and pain sensitivity.
  • Infections: A severe GI infection can trigger post-infectious IBS.
  • Gut microbiota changes: Imbalances in gut bacteria.
  • Food intolerances: Especially FODMAP carbohydrates.
  • Genetics: Family history of IBS increases risk.
  • Psychological factors: Stress, anxiety, and depression exacerbate symptoms.

What are the common triggers for IBS flare-ups?

Common triggers include:

  • Untreated stress, anxiety, and depression
  • Hormonal changes (worse symptoms during menstrual periods)
  • Foods high in FODMAPs, such as:
    • Sugary foods and drinks
    • Dairy products
    • Polyol-rich fruits (apricots, apples, cherries, avocados, nectarines, peaches)
    • Certain vegetables (artichokes, broccoli, onions, asparagus)
    • Legumes (chickpeas, kidney beans, lentils)
    • Sugar alcohols (isomalt, mannitol, maltitol, xylitol, sorbitol)

A food diary and stress management can help identify and avoid triggers.

What are the symptoms of irritable bowel syndrome?

Symptoms vary but often include:

  • Abdominal pain and cramping (often relieved by bowel movements)
  • Bloating and excessive gas
  • Diarrhea, constipation, or alternating between both
  • Mucus in the stool
  • Urgency to use the bathroom
  • Sensation of incomplete evacuation

When should you call your healthcare provider?

Seek immediate care if you experience:

  • Unexplained weight loss
  • Rectal bleeding
  • Unexplained vomiting
  • Abdominal swelling or a palpable mass
  • Shortness of breath or rapid heart rate
  • Pain unrelieved by gas or bowel movement

How is irritable bowel syndrome diagnosed?

Diagnosis is by exclusion and may include:

  • Medical history and symptom assessment
  • Physical exam, including abdominal and rectal exam
  • Rome Criteria: recurrent abdominal pain ≥1 day/week in the last 3 months plus two of:
    • Pain related to bowel movements
    • Change in stool frequency
    • Change in stool form (appearance)
  • Blood tests (to rule out celiac disease, anemia)
  • Stool tests (to exclude infection or inflammation)
  • Food intolerance testing (gluten, lactose)
  • Imaging/endoscopy (colonoscopy or sigmoidoscopy if alarming features present)
  • Hydrogen breath test (small intestinal bacterial overgrowth)

How is irritable bowel syndrome treated?

Treatment tailors to symptoms and may include:

Dietary Changes

  • Low FODMAP diet
  • Increase soluble fiber, decrease insoluble fiber if needed
  • Stay hydrated
  • Keep a food diary to identify triggers

Medications

  • Fiber supplements and laxatives for constipation
  • Anti-diarrheals (loperamide) for diarrhea
  • Antispasmodics (dicyclomine) for cramping
  • Low-dose antidepressants (TCAs, SSRIs) for pain and mood
  • Probiotics to support gut flora
  • IBS-D specific: eluxadoline, alosetron, rifaximin
  • IBS-C specific: lubiprostone, linaclotide

Lifestyle Modifications

  • Regular exercise (≥150 minutes/week)
  • Stress management (yoga, meditation, mindfulness)
  • Adequate sleep (7–9 hours/night)

Psychological Therapies

  • Cognitive Behavioral Therapy (CBT)
  • Gut-directed hypnotherapy

Peppermint oil capsules may also relieve symptoms due to antispasmodic properties.

Sources

  • Irritable Bowel Syndrome. American College of Gastroenterology. Accessed Apr. 22, 2024.
  • Irritable Bowel Syndrome (IBS). National Institute of Diabetes and Digestive and Kidney Diseases. Accessed Apr. 22, 2024.
  • What is IBS? International Foundation for Gastrointestinal Disorders. Accessed Apr. 22, 2024.
  • Irritable Bowel Syndrome. National Library of Medicine (NIH). Accessed Apr. 22, 2024.