Is it really IBS?

IBS is a disorder of gut–brain interaction, affecting how the bowel functions and how the nervous system responds to normal digestive activity.

Common symptoms include:

• Abdominal pain or cramps, often associated with passing stools
• Persistent bloating, excess wind or abdominal distension
• Diarrhoea, urgency or frequent bowel movements
• Constipation, straining or incomplete bowel emptying
• Alternating diarrhoea and constipation
• Mucus in the stool

IBS is generally classified into four types.

IBS-D

Diarrhoea-predominant IBS

Frequent loose stools, urgency and abdominal discomfort.

IBS-C

Constipation-predominant IBS

Hard stools, straining, bloating and abdominal discomfort.

IBS-M

Mixed-type IBS

Alternating episodes of diarrhoea and constipation.

IBS-U

Unclassified IBS

IBS symptoms without a consistent stool pattern.

IBS is usually diagnosed from a characteristic symptom pattern, clinical examination and limited investigations. It is not necessary to perform a colonoscopy on every patient.

For adults with suspected IBS, the usual initial investigations include:

Thyroid function, ferritin, stool infection testing and other investigations may be considered according to symptoms, history and examination.

A normal blood test does not, by itself, establish a diagnosis of IBS. A confident diagnosis also requires assessment of symptoms and consideration of other possible causes.

This is where a more detailed gastroenterology assessment may be helpful.

1. Bile acid diarrhoea (bile acid malabsorption)

An important and sometimes overlooked cause of chronic watery diarrhoea. It may resemble IBS-D, particularly when there is urgency after meals.

Specialist investigations may include a SeHCAT scan or alternative bile acid testing where available.

2. Pancreatic exocrine insufficiency

Reduced pancreatic enzyme production can cause loose stools, bloating, greasy stools and weight loss. It can sometimes be mistaken for IBS.

A faecal elastase test may be useful when clinically indicated. Chronic pancreatitis is a possible underlying cause, but is not synonymous with pancreatic insufficiency.

3. Small intestinal bacterial overgrowth (SIBO)

SIBO may cause bloating, excessive gas, diarrhoea and abdominal discomfort.

Routine breath testing is not recommended for typical IBS. If another disorder is suspected, a specialist will select an appropriate assessment; breath tests have important accuracy limitations.

4. Lactose intolerance and carbohydrate malabsorption

Symptoms may occur after milk, dairy products or other fermentable carbohydrates.

A dietary assessment, lactose elimination and reintroduction, or breath testing may help establish the diagnosis.

An important clinical distinction: Research suggests that approximately one-quarter to one-third of patients labelled as having IBS-D may have bile acid diarrhoea, depending on the population and diagnostic criteria. This figure should not be applied to pancreatic disease, SIBO or all IBS patients collectively.

The aim of further investigation is not to test everyone for every possible condition, but to identify patients whose symptoms justify targeted assessment.

There is no single diet that works for every patient. The best approach depends on whether diarrhoea, constipation, pain or bloating is the predominant symptom.

Start with simple dietary changes

Eat regular meals, avoid large fatty meals, drink adequate water and identify individual food triggers. Soluble fibre, including oats and ispaghula husk, may improve symptoms.

Consider a low-FODMAP diet

A low-FODMAP diet can help reduce bloating, abdominal pain and altered bowel habits. It is best undertaken with an appropriately trained dietitian.

What foods should I avoid with IBS?

Some patients find that onions, garlic, wheat-based products, certain fruits, milk, beans, fizzy drinks and artificial sweeteners worsen symptoms. However, these foods should not automatically be excluded from everyone’s diet.

The low-FODMAP approach usually involves a short restriction phase of approximately 2–6 weeks, followed by structured reintroduction and a personalised long-term diet.

The objective is to eat as widely as possible while controlling symptoms, not to remain on a restrictive diet indefinitely.

Treatment is selected according to the patient’s main symptoms.

Some patients benefit from gut-directed cognitive behavioural therapy or hypnotherapy, particularly when symptoms persist despite initial treatment.

Medication should be reviewed for contraindications, interactions, side effects and individual suitability.

Probiotics contain live microorganisms that may influence the intestinal microbiome.

Some studies suggest that certain probiotics improve bloating, abdominal pain or overall IBS symptoms. However, the research is inconsistent, and there is insufficient evidence to recommend one specific probiotic strain for all patients.

Patients who wish to try a probiotic can consider a trial for 4–12 weeks, monitoring symptoms and discontinuing it if there is no meaningful improvement.

Probiotics are not a cure for IBS, and more expensive products are not necessarily more effective.

IBS can cause significant cramps. New, severe or progressive pain needs medical assessment.

Seek medical assessment if you experience rectal bleeding, unexplained weight loss, iron-deficiency anaemia, a new persistent change in bowel habit, a family history suggesting increased colorectal cancer risk or symptoms that wake you from sleep.

Urgent assessment is appropriate for severe or rapidly worsening abdominal pain, significant bleeding or signs of bowel obstruction.

Beyond IBS. Understanding the real cause of your symptoms.

At GastroClinics, our philosophy is straightforward: a normal initial investigation does not mean that persistent symptoms should be ignored.

Consultant-led gastroenterology assessment

A detailed clinical review to distinguish typical IBS from symptoms that may require further investigation.

Looking beyond routine blood tests

Where clinically appropriate, targeted assessment for bile acid diarrhoea, pancreatic insufficiency, microscopic colitis, lactose intolerance and SIBO.

Advanced gastrointestinal investigations

Access to specialist assessment and appropriate referral pathways for colonoscopy, endoscopy and gastrointestinal physiology investigations.

Personalised long-term management

Evidence-based treatment focused on your predominant symptoms, dietary triggers, lifestyle and response to previous therapies.

Dr Chandra Puli, Consultant Gastroenterologist, has extensive clinical experience in digestive disorders, gastrointestinal endoscopy and the assessment of complex gastrointestinal symptoms.

His approach combines careful clinical assessment, appropriate investigations and individualised treatment, with particular attention to patients who continue to experience symptoms despite previous investigations or treatment.

If your blood tests are normal but you continue to experience abdominal pain, bloating, diarrhoea or constipation, a specialist review may help clarify your diagnosis and treatment options.

GastroClinics London — Specialist Gastroenterology Care

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