With 2 clinics located in Central London and 2 in North-West London, Dr Arun Rajendran takes pride in offering expert, friendly, and effective care for a comprehensive range of conditions affecting the gullet, stomach, colon, and liver.
mailgastro@pm.me
London clinic and Onewelbeck
BMI The Clementine Churchill Hospital
OSD Healthcare
Dr Arun Rajendran provides specialist diagnosis and treatment for collagenous colitis at four private clinics across London — helping patients restore digestive balance and regain control.
Specialist gastroenterologist, London.
Patient Reviews.
Compassionate Specialist Care
Gastroenterology London
Collagenous colitis is a subtype of microscopic colitis — a chronic inflammatory condition of the colon. The bowel appears normal on colonoscopy, but biopsies reveal a thickened collagen band beneath the intestinal lining, disrupting water absorption and causing persistent, watery diarrhoea.
Unlike Crohn's disease, it causes no visible damage, yet it significantly affects daily life. It is most common in middle-aged women, though anyone can be affected. Timely collagenous colitis treatment brings lasting relief.
Microscopic colitis — colon looks normal on the surface
Confirmed by biopsy, not visual examination alone
Most common in women aged 50–70
Not linked to increased bowel cancer ris
Highly treatable with specialist care
The exact cause of collagenous colitis is not fully understood, but several key factors are recognised
The immune system mistakenly attacks the colon lining, driving chronic inflammation and collagen build-up.
A family history of autoimmune conditions or IBD may increase your risk.
Prior gut infections can disrupt the microbiome and trigger a lasting inflammatory response.
Chronic stress, poor diet, and smoking are linked to collagenous colitis flare-ups.
Coeliac disease, rheumatoid arthritis, and thyroid disorders are associated with higher risk.
NSAIDs (e.g. ibuprofen) and proton pump inhibitors (e.g. omeprazole) are among the most common triggers.
Collagenous colitis symptoms often mimic IBS, making specialist assessment essential.
Chronic, watery diarrhoea (often 5–10 times daily)
Abdominal pain and cramping
Bloating and excess wind
Urgent need to reach the toilet
Nocturnal diarrhoea
Persistent fatigue and low energy
Unintentional weight loss
Dehydration
Nausea and reduced appetite
Brain fog and poor concentration
If diarrhoea has persisted for more than four weeks or is disrupting your daily life, seek specialist assessment promptly.
You don't have to manage collagenous colitis alone. Expert, personalised care is available in London.
Because collagenous colitis shows no visible bowel damage, specialist investigation is essential for an accurate diagnosis.
Review of symptoms, medications, diet, and medical history to identify patterns and triggers.
Checking for inflammation markers, nutritional deficiencies, and ruling out infection.
The colon typically looks normal — but this step is essential to obtain accurate biopsy samples.
A thickened subepithelial collagen band of more than 10 micrometres confirms the diagnosis.
CT scan, breath tests, or coeliac screening may be arranged as needed.
Dr. Arun Rajendran tailors every treatment plan to the individual,
based on the latest collagenous colitis treatment guidelines and his extensive clinical experience.
9 mg daily for 6–8 weeks to induce remission
Tapered to 3–6 mg daily for maintenance
Acts locally in the gut with minimal systemic side effects
Thiopurines (e.g. azathioprine) — for ongoing disease
Biologics — for severe, steroid-dependent cases
Review and withdrawal of trigger medications
Loperamide — reduces urgency and frequency
Cholestyramine — helps where bile acid malabsorption is present
Oral rehydration therapy to replace fluids and electrolytes
Regular reviews to monitor treatment response
Clear, agreed plan for managing a collagenous colitis flare-up
Nutritional support and ongoing specialist guidance
The right nutritional and lifestyle approach, combined with medical treatment, can significantly reduce flare-ups and improve quality of life.
Reduce gluten and lactose during active symptoms
Include anti-inflammatory foods — oily fish, turmeric, leafy greens
Limit caffeine, alcohol, and processed foods
Choose low-fibre, easily digestible options during a flare-up
Eat smaller, more frequent meals
Manage stress with yoga, mindfulness, or breathing exercises
Stay well hydrated — aim for 1.5–2 litres of water daily
Keep a symptom and food diary to spot patterns
Discuss all medications with your doctor, including OTC pain relief
Engage in gentle exercise — walking, swimming, or yoga
Follow a low-fat diet during symptomatic periods
Avoid smoking
Prioritise quality sleep to support gut healing
With over a decade of experience, Dr Arun provides expert, friendly gastro care, listening carefully and offering personalised attention because you deserve more than a rushed appointment.
Thorough investigation before treatment, with a clear explanation in plain English.
Every plan is built around your specific diagnosis and lifestyle, not a generic protocol.
Continued follow-up, flare-up management, and access to a wider specialist network across London.
Conveniently located across central and south London, often available within days.
Thousands of patients across London and the UK have trusted
Dr. Arun Rajendran to get to the bottom of their digestive symptoms.
We are a self-pay clinic but also accept all major UK healthcare insurance providers.
Our London Clinic Locations
20 Devonshire Place, London, W1G 6BW (Wed: 17:45 – 19:30).
Welbeck Street, London, W1G 0AR (Mon: 18:00 – 20:00).
Sudbury Hill, Harrow, HA1 3RX
(Tue 18:00–20:00 · Alt Sat 08:30–10:30).
One Medical House, Hemel Hempstead, HP2 7YU
(Saturday: 09:00 – 11:00).