Can an online test tell me if I have IBS?

No. Only a healthcare professional can diagnose IBS and rule out other causes. This tool helps you understand and describe your symptoms.

Which symptoms need a doctor straight away?

Blood in your stool, black or tar-like stool, unexplained weight loss, symptoms that wake you at night, fever, or a new change in bowel habits after 50 should always be checked.

What happens at a GP appointment for IBS?

Usually a conversation about your symptoms, an examination and sometimes blood or stool tests to rule out other conditions.

Free Thesos tool · Piece: Symptoms

Could Your Symptoms Fit an IBS Pattern?

See how closely your symptoms overlap with common IBS-like patterns and check important warning signs.

~3 min Your symptom overlap and a safety check

Your answers are not saved to your Thesos account unless you choose to save them. Educational, not a diagnosis.

About this tool, FAQ and sources

IBS usually involves recurring tummy pain linked to bowel movements, together with changes in stool. This checker compares your answers with commonly reported IBS features and explains the overlap. It never gives a diagnosis or a probability.

How it works

You answer original questions about pain, how it relates to bowel movements, bloating, stool changes, duration and context, plus a separate safety section. The result describes how many commonly reported IBS features appear in your answers and why. If you select a warning sign, the safety message comes first.

It can

Explain which of your symptoms are commonly described in IBS
Highlight warning signs that need a doctor
Help you prepare for a GP appointment

It cannot

Diagnose IBS or any other condition
Rule out other conditions such as coeliac disease or inflammatory bowel disease
Give a probability that you have IBS

Questions

Can an online test tell me if I have IBS?: No. Only a healthcare professional can diagnose IBS and rule out other causes. This tool helps you understand and describe your symptoms.
Which symptoms need a doctor straight away?: Blood in your stool, black or tar-like stool, unexplained weight loss, symptoms that wake you at night, fever, or a new change in bowel habits after 50 should always be checked.
What happens at a GP appointment for IBS?: Usually a conversation about your symptoms, an examination and sometimes blood or stool tests to rule out other conditions.

Method and sources

Original Thesos overlap rule (v1.0), based on features described by NIDDK and NICE: recurring abdominal pain, its relation to bowel movements, changes in stool, and duration. It is not a diagnostic algorithm.

Symptoms & Causes of IBS · NIDDK
Diagnosis of IBS · NIDDK
Irritable bowel syndrome in adults (CG61) · NICE (UK)
Irritable bowel syndrome (IBS) · NHS (UK)
ACG Clinical Guideline: Management of IBS (2021) · American College of Gastroenterology
Irritable Bowel Syndrome · MedlinePlus, U.S. National Library of Medicine

Evidence sources last reviewed: 15 October 2026Last updated: 15 October 2026

For education and self-management only. Not a diagnosis. In an emergency, call your local emergency number.