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Chronic diarrhoea, defined as loose stools lasting more than four weeks, is caused most commonly by irritable bowel syndrome, inflammatory bowel disease, malabsorption syndromes, or chronic infections, with rarer causes including microscopic colitis, bile acid malabsorption, and gastrointestinal malignancy. Specialist referral is warranted when alarm features are present, when symptoms persist despite first-line treatment, or in patients over fifty regardless of severity. The symptoms overlap considerably between these conditions, and a structured workup is what separates them.
According to Dr. Vipulroy Rathod, Gastroenterologist in Mumbai, “Most chronic diarrhoea in Indian patients gets treated empirically with antibiotics or anti-motility agents without anyone working out what’s actually going on. Some have IBS and need lifestyle advice. Some have IBD that’s been missed for years. Some have lactose intolerance or coeliac disease that a simple test would have picked up. Empirical treatment without diagnosis is how the underlying cause stays hidden.”
What are the common causes of chronic diarrhoea?
The diagnosis usually narrows down based on stool pattern, associated symptoms, and a few targeted tests rather than a shotgun approach.
- Irritable bowel syndrome. The commonest cause overall. Crampy pain, alternating bowel habits in some patients, urgency, no blood, no weight loss. IBS is a real diagnosis with biological underpinnings, not a label for unexplained symptoms. It is also a diagnosis of exclusion that requires ruling out organic causes first.
- Inflammatory bowel disease produces diarrhoea with blood, urgency, nocturnal symptoms, weight loss, and raised inflammatory markers. Patients often spend years being treated for IBS before someone runs a calprotectin or arranges a colonoscopy.
- Malabsorption syndromes. Coeliac disease, pancreatic insufficiency, bile acid malabsorption, small intestinal bacterial overgrowth. These cause bulky, fatty, sometimes pale stools, often with weight loss and bloating disproportionate to the diarrhoea. Testing for each is straightforward once the pattern is recognised.
- Microscopic colitis often gets missed because the colon looks normal on endoscopy. Diagnosis requires biopsies even when the mucosa appears unremarkable. The condition affects older patients particularly and is sometimes triggered by NSAIDs, PPIs, or SSRIs.
A few less common but important causes need to stay on the radar. Endoscopy in Mumbai services with colonoscopy, random biopsy capability, push enteroscopy, and capsule endoscopy in selected cases are what allow these diagnoses to be made when the standard workup hasn’t given clear answers.
When chronic diarrhoea warrants specialist referral?
Not every patient with chronic diarrhoea needs a gastroenterologist. Specific features should prompt referral rather than another round of empirical treatment.
Alarm symptoms come first on the list. Blood in the stool. Weight loss. Nocturnal diarrhoea waking the patient from sleep. Iron deficiency anaemia. Family history of colorectal cancer or IBD. Any one of these features changes the workup completely, and they shouldn’t be managed in primary care without specialist input.
Age matters as much as symptoms. Chronic diarrhoea starting after fifty has a different differential than the same symptoms in a twenty-five-year-old. The probability of inflammatory bowel disease falls with age, while microscopic colitis, ischaemic colitis, and malignancy rise. The threshold for colonoscopy is lower in this group regardless of how mild the symptoms appear.
Failure to respond to first-line management is another clear trigger. Patients tried on dietary modification, anti-motility agents, or empirical antibiotics for several weeks without improvement need a proper workup. Persisting with treatments that aren’t working delays the actual diagnosis.
The fourth situation is when the diagnosis matters for the patient’s long-term care. Coeliac disease needs lifelong gluten avoidance. IBD needs specific treatment and surveillance. Bile acid malabsorption responds to cholestyramine. None of these can be managed properly without a diagnosis, and trial-and-error rarely arrives at the right answer. Read more on what IBD is and how it’s diagnosed for one of the more important differential diagnoses in chronic diarrhoea that frequently gets missed in primary care.
Why choose Dr. Vipulroy Rathod for chronic diarrhoea assessment?
Dr. Vipulroy Rathod has been assessing and managing chronic diarrhoea at Fortis Hospital Mulund for over three decades, with the structured workup that separates IBS from IBD from malabsorption from rarer diagnoses without putting every patient through every test. The history and examination drive most of what gets tested, but the threshold for organic disease screening is appropriately low in patients with any alarm features or with a presentation that doesn’t fit cleanly into IBS.
The bigger problem patients face isn’t access to tests. It’s getting the right tests in the right order. Some patients arrive having had multiple stool cultures and ultrasounds when a colonoscopy with biopsies would have answered the question in one appointment. Others arrive after years of being managed for IBS when their actual diagnosis was coeliac disease or microscopic colitis. Working through the differential properly is what makes the difference.
Book your consultation today with one of India’s most experienced specialists for chronic diarrhoea assessment and diagnosis.
Frequently Asked Questions
When it lasts more than four weeks. Anything shorter is usually acute or subacute, with a different differential weighted heavily towards infection.
No. The threshold depends on age, alarm features, and clinical pattern. Young patients with classical IBS features and no alarm symptoms often don’t need a scope. Older patients, those with any alarm feature, or those who haven’t responded to first-line management usually do.
Full blood count, CRP, faecal calprotectin, stool infection screen, coeliac serology, and thyroid function as the starting set. Pancreatic faecal elastase, bile acid testing, and SIBO breath tests come in selectively based on the clinical picture.
Yes, in functional cases like post-infectious IBS that improves over months. Persistent organic disease doesn’t usually resolve without specific treatment, which is why a proper diagnosis matters before assuming things will settle.
Reference links-
- Chronic Diarrhoea Guidelines, American College of Gastroenterology — https://gi.org/guideline/diarrhea-in-the-adult/
- Chronic Diarrhoea Management Standards, World Gastroenterology Organisation — https://www.worldgastroenterology.org/guidelines
