Irritable Bowel Syndrome (IBS)

What Is Irritable Bowel Syndrome?

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by recurrent abdominal pain associated with changes in bowel habits. Unlike inflammatory bowel disease (IBD), IBS does not cause visible inflammation, ulcers, or structural damage to the digestive tract. However, it can significantly impact quality of life and daily functioning.

IBS affects an estimated 10 to 15% of the global population, making it one of the most commonly diagnosed gastrointestinal conditions. It is more prevalent in women and is most frequently diagnosed in people under the age of 50. IBS is classified into subtypes based on the predominant bowel pattern:

IBS-D (diarrhea-predominant): More than 25% of stools are loose or watery
IBS-C (constipation-predominant): More than 25% of stools are hard or lumpy
IBS-M (mixed): Both diarrhea and constipation occur frequently
IBS-U (unsubtyped): Does not clearly fit into the above categories

Common Symptoms

The defining symptom of IBS is recurrent abdominal pain, occurring on average at least one day per week over the past three months, associated with two or more of the following:

Pain related to defecation: Symptoms may improve or worsen with bowel movements
Change in stool frequency: More frequent or less frequent bowel movements
Change in stool form: Stools may become harder, looser, or alternate between both

Additional symptoms commonly reported by IBS patients include:

Abdominal bloating and distension: Often worsening throughout the day
Excessive gas (flatulence)
Mucus in the stool
Urgency: A sudden need to find a bathroom, particularly in IBS-D
Feeling of incomplete evacuation
Nausea
Fatigue and difficulty sleeping
Anxiety and depression: Commonly co-occur with IBS due to the gut-brain connection

Causes and Risk Factors

The exact cause of IBS is not fully understood, but it is now recognized as a disorder of gut-brain interaction (DGBI). Multiple factors contribute to the development and persistence of symptoms:

Altered gut motility: Abnormal contractions of the intestinal muscles — too strong or too weak — can cause diarrhea or constipation respectively
Visceral hypersensitivity: Heightened sensitivity of the nerves in the GI tract, causing normal amounts of gas or stool movement to be perceived as painful
Gut-brain axis dysfunction: Miscommunication between the brain and the enteric nervous system of the gut, amplifying pain signals and altering motility
Post-infectious IBS: Approximately 10 to 15% of IBS cases develop after an acute episode of bacterial gastroenteritis (such as Salmonella or Campylobacter infection)
Small intestinal bacterial overgrowth (SIBO): An imbalance in the bacteria of the small intestine may contribute to bloating, gas, and diarrhea
Food sensitivities: Certain foods, particularly those high in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), can trigger symptoms
Stress and psychological factors: Chronic stress, anxiety, depression, and history of trauma are strongly associated with IBS
Genetics: Having a family member with IBS increases your risk
Altered gut microbiome: Changes in the composition of intestinal bacteria may play a role

Diagnosis

IBS is diagnosed based on symptom criteria (Rome IV criteria) and the exclusion of other conditions. Dr. Khan performs a comprehensive evaluation that may include:

Detailed symptom assessment: Duration, pattern, triggers, and associated symptoms
Physical examination: Including abdominal and rectal exam
Blood tests: Complete blood count, inflammatory markers (CRP), celiac serology (tissue transglutaminase antibody), and thyroid function tests
Stool tests: Fecal calprotectin to rule out inflammatory bowel disease, stool cultures, and testing for ova and parasites
Colonoscopy: Recommended for patients over 45, those with alarm symptoms (rectal bleeding, weight loss, anemia), or when there is a family history of colorectal cancer or IBD
Hydrogen breath test: To evaluate for lactose intolerance, fructose malabsorption, or small intestinal bacterial overgrowth (SIBO)

Treatment Options

IBS management requires a personalized, multimodal approach. Dr. Khan works with each patient to develop a treatment plan that addresses their specific symptom pattern and triggers.

Dietary Interventions

Low FODMAP diet: A structured elimination and reintroduction diet that has been shown to improve symptoms in up to 75% of IBS patients. Dr. Khan can guide you through this process or refer you to a specialized dietitian
Fiber optimization: Soluble fiber (psyllium) is generally beneficial, while insoluble fiber (bran) may worsen symptoms in some patients
Identifying trigger foods: Common triggers include caffeine, alcohol, carbonated beverages, fatty foods, artificial sweeteners, and dairy products
Regular meal timing: Eating at consistent times and avoiding large meals

Medications

Medications are selected based on the predominant symptom pattern:

For IBS-D: Loperamide (Imodium) for diarrhea; eluxadoline (Viberzi) for pain and diarrhea; rifaximin (Xifaxan) for bloating and diarrhea; bile acid sequestrants (cholestyramine) if bile acid malabsorption is suspected
For IBS-C: Linaclotide (Linzess), plecanatide (Trulance), or lubiprostone (Amitiza) to increase intestinal fluid and promote bowel movements; tegaserod for women under 65 with constipation-predominant symptoms
For pain and bloating: Antispasmodics (hyoscyamine, dicyclomine) to reduce intestinal muscle spasms; peppermint oil capsules
Neuromodulators: Low-dose tricyclic antidepressants (amitriptyline, nortriptyline) for pain relief in IBS-D; SSRIs (sertraline, paroxetine) for IBS-C with comorbid anxiety or depression

Psychological Therapies

Because of the strong gut-brain connection in IBS, psychological interventions can be highly effective:

Cognitive behavioral therapy (CBT): The most studied psychological treatment for IBS, shown to reduce symptoms and improve coping strategies
Gut-directed hypnotherapy: Proven effective in multiple clinical trials, with benefits often lasting long after treatment ends
Mindfulness-based stress reduction (MBSR): Helps manage stress and reduce symptom perception

Probiotics

Certain probiotic strains have shown benefit in IBS, particularly for bloating and overall symptom improvement. Dr. Khan can recommend specific evidence-based probiotic formulations based on your symptoms.

When to See a Doctor

While IBS is not life-threatening, it is important to seek medical evaluation if you experience:

Persistent changes in bowel habits that interfere with daily life
Rectal bleeding or blood in the stool
Unexplained weight loss
Symptoms that begin after age 50
Nighttime symptoms that wake you from sleep
Progressive worsening of symptoms despite dietary changes
Iron deficiency anemia
A family history of colorectal cancer, inflammatory bowel disease, or celiac disease

Dr. Amber Khan at GastroCares takes IBS seriously and provides comprehensive, empathetic care to help patients manage their symptoms effectively and regain control of their daily lives.