Irritable bowel syndrome (IBS) is a common chronic condition affecting 20–50% of patients with gastrointestinal complaints. The exact pathophysiology is unknown, but may involve changes in gastrointestinal motility, visceral hypersensitivity, and altered gastrointestinal permeability. The condition presents with recurrent, non‑specific changes in bowel movements (e.g., diarrhea and/or constipation) and abdominal symptoms (e.g., diffuse pain, pressure). The Rome IV diagnostic criteria, which are based on alterations in bowel habits, are used to diagnose IBS. Laboratory studies and imaging reveal no abnormalities. Treatment consists of dietary modifications and administration of symptom‑based medication (antidiarrheals, laxatives, antispasmodics).
- Prevalence: 10–20% in North America and Europe (accounts for 20–50% of referrals to gastroenterologists)
- Sex: : In Western countries, women are 1.5–2 times more likely to be affected than men.
- Age: highest prevalence in individuals aged 20–39 
Epidemiological data refers to the US, unless otherwise specified.
IBS is a functional gastrointestinal disorder without a specific organic cause. The pathophysiological processes leading to IBS are multifaceted and not yet fully understood. The most common findings associated with IBS are:
- Altered gastrointestinal motility
- Visceral hypersensitivity/hyperalgesia
- Altered permeability of the gastrointestinal mucosa
- Psychosocial aspects
IBS is characterized by chronic abdominal pain and changes in bowel habits – both of which are typical, but not specific, symptoms of the condition.
- Frequency, intensity, and localization generally vary widely from patient to patient
- Typically related to defecation
- Altered bowel habits: diarrhea and/or constipation
Other gastrointestinal symptoms
- Nausea, reflux, early satiety
- Passing of mucus, abdominal bloating
- Extraintestinal symptoms
- Physical examination: normal
Subtypes and variants
Four different patterns are seen in the presentation of irritable bowel syndrome:
- IBS‑D (diarrhea is the predominant symptom)
- IBS‑C (constipation is the predominant symptom)
- IBS‑M (mixed diarrhea and constipation)
- IBS‑A (alternating diarrhea and constipation)
IBS is a clinical diagnosis; based on the patient's history (Rome IV criteria) and symptoms. However, any suspected differential diagnoses should be ruled out before making a definitive diagnosis.
- Rome IV criteria for irritable bowel syndrome: diagnosis can be made if the following criteria are present
- Other symptoms consistent with IBS (see "Symptoms/clinical findings")
- A family history of inflammatory bowel disease, celiac disease, or colorectal cancer is unusual in patients with IBS.
Ruling out organic disease
If no other differential diagnosis is suspected, laboratory tests and imaging are generally not recommended for individuals under the age of 50 if they show typical signs of IBS and lack any alarming signs, such as iron-deficiency anemia, weight loss, or a family history of organic gastrointestinal diseases.
|General appearance||Pain||Stool habits|
|Irritable bowel syndrome|| || |
|Crohn disease|| || |
|Ulcerative colitis|| || || |
|Colorectal carcinoma|| || |
Other differential diagnoses to consider
- Bacterial or viral gastroenteritis
- Bacterial overgrowth syndrome (i.e., )
The differential diagnoses listed here are not exhaustive.
- Regular consultations and reassurance that the disease, although chronic, is benign
- Dietary adjustments
- Physical activity
- Stress management (identification of stress factors, avoidance techniques, relaxation therapy)
- Psychological therapy (patients with psychological conditions): e.g., cognitive-behavioral therapy
Medical therapy of IBS is symptom‑directed:
- Diarrhea Constipation