Irritable Bowel Syndrome (IBS)
Irritable bowel syndrome (IBS) is a functional gut-brain disorder involving abdominal pain linked to changes in bowel habits, diagnosed per the Rome IV criteria and treated per the American College of Gastroenterology (ACG) 2021 Clinical Guideline.
Symptoms
Recurrent abdominal pain, on average at least 1 day per week over the past 3 months, associated with a change in stool frequency or form (constipation, diarrhea, or a mix), plus often bloating.
Causes and risk
A disrupted gut-brain axis, altered gut motility and sensitivity, and sometimes a prior gut infection; stress and certain foods commonly trigger flares rather than cause the underlying condition.
How it is evaluated
The Rome IV criteria allow IBS to be diagnosed positively based on symptoms, without requiring extensive testing to rule out every other condition first -- consistent with current guideline emphasis, per the ACG guideline. Alarm features (bleeding, unintended weight loss, onset after age 50, nighttime symptoms, anemia, family history of colorectal cancer or IBD) argue against IBS and warrant further workup.
Treatment
A time-limited low-FODMAP diet (restriction, then structured reintroduction) is a first-line dietary approach; medications are tailored to the predominant symptom (antispasmodics, subtype-specific agents), per the ACG guideline, which specifically advises against routine SSRIs for IBS and cautions against staying on a restrictive diet indefinitely without reintroduction, to avoid nutritional deficiencies.
When to seek care
Rectal bleeding, unintended weight loss, iron-deficiency anemia, nighttime symptoms that wake you from sleep, or new symptoms after age 50 are alarm features that warrant prompt evaluation rather than being assumed to be IBS.