Irritable bowel syndrome (IBS): symptoms, assessment and GP advice

Irritable bowel syndrome, often shortened to IBS, is a common condition affecting how the gut functions. It causes ongoing or recurrent abdominal symptoms without evidence of structural bowel disease.

This page explains how GPs assess IBS-style symptoms, how the diagnosis is made, and what helps manage symptoms safely.

These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help, please book an appointment with one of our GP’s.

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Common symptoms of IBS

IBS symptoms vary between individuals and may fluctuate over time.

Typical features include:

Recurrent abdominal pain or cramping
Bloating or abdominal distension
Changes in bowel habit, such as diarrhoea, constipation, or both
Relief of pain after opening the bowels
Mucus in the stool

Symptoms often worsen during periods of stress or after certain foods.

Seek urgent medical advice if you have:

Persistent or severe abdominal pain
Unexplained weight loss
Blood in the stool
Persistent night-time symptoms
New bowel symptoms after the age of 50

Types of IBS symptoms

IBS is sometimes described by the predominant bowel pattern:

IBS with constipation
IBS with diarrhoea
Mixed IBS

These patterns may change over time.

What causes IBS

The exact cause of IBS is not fully understood. Contributing factors may include:

Increased gut sensitivity
Altered bowel movement patterns
Changes in gut brain signalling
Previous gut infection
Stress or anxiety

IBS is considered a functional bowel disorder, meaning symptoms occur despite normal structure and test results.

How GPs diagnose IBS

IBS is usually diagnosed based on:

A typical symptom pattern
Duration of symptoms
Absence of red flag features

Basic tests may be done to rule out other conditions, but extensive investigation is usually not required when symptoms fit IBS.

Tests that may be considered

A GP may consider limited tests if appropriate, such as:

Blood tests to exclude inflammation or anaemia
Coeliac disease screening
Stool tests if diarrhoea is prominent
In some cases, onward referral may be needed

Normal results support a diagnosis of IBS.

Managing IBS symptoms

Management is individual and often involves a combination of approaches.

Diet and lifestyle

Regular meals
Avoiding large or skipped meals
Identifying individual trigger foods gradually
Eating whole foods, avoiding ultra-processed foods
Staying physically active

Some people benefit from dietitian-guided dietary changes.

Bowel habit management

Treating constipation or diarrhoea appropriately
Avoiding unnecessary laxatives or anti diarrhoeals

Stress and gut sensitivity

Managing stress and sleep
Recognising the gut brain connection
Psychological support where symptoms are severe or persistent

Gut microbiome and IBS: what we know

The gut microbiome refers to the community of bacteria and other microbes living in the bowel. Research suggests the microbiome can play a role in IBS symptoms for some people, alongside gut sensitivity and gut brain signalling.

IBS is linked to gut brain signalling and the microbiome may contribute to symptoms in a subset of patients, particularly after a gut infection.
Diet can change symptoms and the microbiome. Approaches such as reducing trigger foods and structured dietary plans (often with a dietitian) can be helpful, but they should be personalised rather than restrictive by default.
Probiotics are mixed evidence. Some guidelines suggest probiotics may help some people, but results vary by strain and person. A practical approach is a time-limited trial and stopping if there is no clear benefit.
Faecal microbiota transplant (FMT) is not a routine treatment for IBS. Studies show inconsistent results and it is generally restricted to research settings rather than standard care.

If you are considering probiotics or diet changes for IBS, a GP can help you choose a safe, sensible plan and check for red flags that need further investigation.

Medications for IBS

Medication may be considered if lifestyle measures are not enough. The choice depends on symptoms and should be reviewed regularly.

Long-term medication is not always needed.

The low FODMAP diet and IBS

The low FODMAP diet is a structured dietary approach that reduces certain carbohydrates which are poorly absorbed in the gut and can trigger bloating, pain and altered bowel habit in some people with IBS.

There is good evidence that a low FODMAP approach can improve IBS symptoms in some people, particularly bloating and abdominal pain.
It is not intended as a permanent diet. The diet involves a short restriction phase followed by gradual reintroduction to identify individual triggers.
Not everyone needs it. Many people manage IBS symptoms with simpler changes such as regular meals, reducing large portions, and identifying personal triggers.
Dietitian support is recommended where possible, as unnecessary long-term restriction can affect nutrition and gut health.

A GP can help you decide whether a low FODMAP diet is appropriate, and whether referral to a dietitian would be beneficial.