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Published on: 1/29/2026
Recurring abdominal pain linked to changes in bowel habits is the biggest and most defining symptom of IBS, often changing with or after a bowel movement. There are several factors to consider that can affect diagnosis and next steps, including the specific stool pattern, other common symptoms, and red flags that require medical attention; see below for the complete answer.
When people ask about IBS (Irritable Bowel Syndrome), they often want to know the single biggest symptom to watch for. The most accurate, medically supported answer is this:
The biggest and most defining symptom of IBS is ongoing abdominal pain or discomfort that is linked to changes in bowel habits.
This pain–bowel change connection is what separates IBS from many other digestive problems. While IBS can cause several symptoms, abdominal pain tied to bowel movements is the core feature doctors use to identify the condition.
Below, we'll break this down in clear, everyday language—what the pain feels like, why it happens, how it shows up differently in different people, and when it's important to seek medical care.
IBS is a functional gut disorder, meaning the digestive tract looks normal on tests but doesn't work as smoothly as it should. It affects how the intestines move, sense pain, and respond to food and stress.
IBS is common and long-lasting, but it does not cause cancer, does not damage the intestines, and does not shorten life expectancy. That said, it can significantly affect quality of life if symptoms are not managed.
Abdominal pain is considered the hallmark symptom of IBS because it has three key features:
Doctors around the world use these criteria when diagnosing IBS.
People with IBS often describe the pain as:
The pain may be mild one day and more intense the next. It often comes and goes rather than staying constant.
IBS pain happens due to a mix of factors rather than a single cause:
These factors can make normal digestion feel uncomfortable or painful.
Abdominal pain alone is not enough to define IBS. The pain must be linked to bowel habit changes.
Diarrhea (IBS-D)
Frequent, loose, or urgent stools
Constipation (IBS-C)
Hard stools, straining, or feeling like you didn't fully empty
Mixed type (IBS-M)
Alternating between diarrhea and constipation
These patterns may shift over time, which can be frustrating but is typical for IBS.
While abdominal pain is the biggest symptom, many people experience additional issues that add to discomfort:
These symptoms support the diagnosis but are not considered the main defining feature.
Understanding what IBS does not cause is just as important:
If any of these occur, they may point to another condition and should be evaluated by a doctor.
There is no single test for IBS. Diagnosis is based on:
If you're experiencing recurring abdominal pain along with changes in your bowel habits, it may help to check whether your symptoms align with Irritable Bowel Syndrome (IBS) using a free AI-powered symptom checker before your doctor's appointment.
While IBS itself is not dangerous, some symptoms should never be ignored. Speak to a doctor promptly if you experience:
These signs may indicate a more serious condition and require medical evaluation.
IBS can be uncomfortable and disruptive, but many people learn to manage it well over time. Symptom control often improves with:
IBS symptoms often fluctuate, and having good days and bad days is normal.
The biggest symptom of IBS is recurring abdominal pain that is directly linked to changes in bowel habits. This combination—not bloating alone, not diarrhea alone, and not constipation alone—is what defines IBS.
If your symptoms fit this pattern, you're not alone, and help is available. Take a moment to use a free online tool to assess your symptoms for Irritable Bowel Syndrome (IBS), then speak to a doctor about your symptoms—especially if anything feels severe, unusual, or potentially serious.
A clear diagnosis is the first step toward relief and peace of mind.
(References)
* Barbara G, et al. Symptoms and Burden of Irritable Bowel Syndrome: An Overview. Exp Brain Res. 2018 Sep;236(9):2489-2495. doi: 10.1007/s00221-018-5321-y. Epub 2018 Jul 11. PMID: 29995166.
* Ford AC, et al. Irritable Bowel Syndrome: A Clinical Review. JAMA. 2020 Feb 25;323(8):769-781. doi: 10.1001/jama.2020.0094. PMID: 32100827.
* Van Oudenhove L, et al. Pain perception in irritable bowel syndrome. Handb Clin Neurol. 2019;168:207-224. doi: 10.1016/B978-0-444-64016-1.00013-0. PMID: 32183758.
* Camilleri M. The Irritable Bowel Syndrome: Diagnosis, Pathogenesis and Treatment. Dig Dis. 2018;36(1):5-14. doi: 10.1159/000481232. Epub 2017 Dec 22. PMID: 29281881.
* Sperber AD, et al. Patient-reported outcomes and burden of irritable bowel syndrome. World J Gastroenterol. 2018 Nov 14;24(42):4750-4760. doi: 10.3748/wjg.v24.i42.4750. PMID: 30487608; PMCID: PMC6238053.
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