There's no single test for IBS (irritable bowel syndrome). Doctors diagnose it from a recognizable pattern of symptoms, set out in the Rome IV criteria, plus a few simple tests to rule out conditions that look similar.[2][3] That makes a structured self-check a sensible first step, as long as you treat the result as a reason to talk to a doctor rather than as a diagnosis. About 4% of adults worldwide meet the Rome IV criteria in internet surveys.[1]
Do I have IBS? A Rome IV self-check
Think about the last three months and answer these four questions:
- Pain: Have you had belly pain on at least one day a week, on average?
- A link to your bowels: Does the pain go with at least two of these?
- It's related to bowel movements (it eases or gets worse when you go).
- It comes with a change in how often you go.
- It comes with a change in what your stool looks like, harder or looser than usual.
- Duration: Did these symptoms first start at least six months ago?
- No red flags: Are you free of every warning sign in the list further down this page?
If you answered yes to all four, your symptoms fit the pattern doctors use to diagnose IBS.[3][2] Bloating is common in IBS, but you don't need it for the diagnosis.[2] If you have bowel changes or bloating without pain, Rome IV classifies them differently, for example as functional constipation, functional diarrhea or functional abdominal bloating.[3] The newer Rome V criteria, published in 2026, count abdominal discomfort alongside pain again and set a lower minimum symptom frequency than Rome IV.[4]
When to suspect IBS: the pattern above is the main clue. In most people IBS comes and goes over time, flaring and settling, and it's more common in young adult women.[5] It often starts after a stomach bug: in a meta-analysis of 45 studies, about 1 in 10 people had IBS a year after an episode of infectious gastroenteritis.[6]
Which type of IBS do I have?
IBS has four subtypes. They depend on your usual stool type on the days when your bowel movements are abnormal, measured with the Bristol Stool Form Scale, where types 1–2 are hard and lumpy and types 6–7 are mushy or watery.[2]
| Subtype | Your abnormal bowel movements |
|---|---|
| IBS-C (constipation) | More than 25% are type 1–2, and fewer than 25% are type 6–7 |
| IBS-D (diarrhea) | More than 25% are type 6–7, and fewer than 25% are type 1–2 |
| IBS-M (mixed) | More than 25% are type 1–2 and more than 25% are type 6–7 |
| IBS-U (unclassified) | You meet the IBS criteria, but your stools don't fit any of these patterns |
The American College of Gastroenterology (ACG) suggests working out your subtype from a daily stool diary kept for two weeks, while you're off any medicines that affect your bowels. Your subtype matters because it guides which tests and treatments make sense. It can also change: more than half of people with IBS switch predominant subtype within a year.[2]
Is it IBS or something else?
Several conditions can cause IBS-like symptoms, which is why a doctor checks for them before settling on IBS:
- Celiac disease, an immune reaction to gluten. In a meta-analysis cited by the ACG, 3.3% of people with IBS symptoms had biopsy-proven celiac disease.[2] See IBS vs celiac disease.
- Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis. Symptoms alone can't always separate it from IBS with diarrhea, but IBD is uncommon in people with IBS symptoms: the ACG cites a pretest probability of under 0.5% to 1.2%.[2] See IBS vs Crohn's disease.
- Microscopic colitis, an inflammation of the colon. UK guidelines list female sex, severe or watery diarrhea, diarrhea at night, diarrhea that started less than 12 months ago, weight loss, and medicines such as NSAIDs and proton pump inhibitors as features that make it more likely, and suggest a colonoscopy in that situation.[7]
- Bile acid diarrhea, which UK guidelines suggest testing for if diarrhea wakes you at night or you've had your gallbladder removed.[7]
- Colorectal cancer, which is uncommon in people with typical IBS symptoms but important not to miss. See IBS or colon cancer.
When should you see a doctor before assuming it's IBS?
These alarm features aren't explained by IBS. If you have any of them, see a doctor promptly:[2][5][8]
- Blood in or on your stool, or black, tarry stools
- Weight loss you didn't intend
- Anemia (a low blood count) on a blood test
- Fever
- Symptoms that wake you up at night
- A lump or swelling in your abdomen
- A family history of colorectal cancer, IBD or celiac disease
- Symptoms that started after about age 50
On their own, alarm features have a low predictive value for serious disease in people with IBS symptoms,[2] so having one isn't a reason to panic. It is a reason not to assume IBS. Get urgent care for heavy bleeding, severe or worsening pain, or feeling faint. Read more about IBS red flags.
What will a doctor do next?
Both US and UK guidelines recommend a "positive diagnosis": your doctor diagnoses IBS from your symptoms once red flags have been checked and a few basic tests are normal, instead of ordering test after test to exclude everything.[2][7] Expect:
- Questions and an examination, covering your symptom pattern, red flags, medicines and family history.[5][7]
- Blood tests. UK guidelines advise a full blood count, CRP or ESR (markers of inflammation) and a celiac blood test for everyone presenting with IBS symptoms for the first time.[7] The ACG recommends celiac testing for people with diarrhea symptoms.[2] Keep eating gluten until this is done, because the test relies on it.[9]
- A stool test such as fecal calprotectin, which helps rule out IBD if you have diarrhea.[2][7]
- A colonoscopy only if needed. The ACG recommends against routine colonoscopy for IBS symptoms in people under 45 without warning signs.[2]
For the details of each test, see how IBS is diagnosed.
What should you track before your appointment?
A couple of weeks of notes make the appointment far more useful, and they're what the ACG suggests for pinning down your subtype.[2] Note the days you have pain and whether it eases or worsens around bowel movements, your stool type and how often you go, the time of day (including at night), what you ate, and any blood, weight change or fever. A food and symptom diary on paper works. IBS Clue, an iPhone app coming soon, records quick symptom check-ins and Bristol stool types and exports them as a PDF report for your doctor. It's a tracking tool and doesn't diagnose IBS.