Collagenous Colitis

Overview

Collagenous colitis is a condition that causes long-lasting or repeated bouts of watery diarrhoea (loose, watery stools). It is one type of a group of conditions called 'microscopic colitis'. That name means the inside of your bowel looks normal when a doctor looks at it directly, but tiny changes can be seen when a small tissue sample is checked under a microscope. In collagenous colitis, a thin band of a protein called collagen builds up just under the surface of the bowel lining. This is not cancer, and it does not turn into cancer. It is an inflammation problem in the large bowel (colon) that can usually be managed well.

It is more common than doctors once thought, especially in people over 50. It is now diagnosed more often because doctors are more aware of it and are more likely to take tissue samples during bowel tests. Many people with ongoing watery diarrhoea turn out to have a form of microscopic colitis.

It most often affects adults between about 50 and 70 years old, and it is around three to four times more common in women than in men. It can happen at any adult age, and it is rare in children. Some people with collagenous colitis also have another condition where the immune system attacks the body's own tissues, such as an underactive thyroid, coeliac disease, or rheumatoid arthritis.

Symptoms

Common symptoms

• Ongoing or recurring watery diarrhoea — the stools are loose and watery rather than solid
• A sudden, urgent need to open your bowels, sometimes hard to hold in
• Needing to go to the toilet during the night
• Crampy tummy pain or discomfort, often easing after a bowel movement
• Bloating, wind and a gurgling feeling in the belly
• Feeling you still need to go even after you have been
• Losing a little weight without trying
• Feeling tired or washed out, sometimes because of lost fluids and salts
• Occasional accidental leakage of stool (incontinence), which can be distressing but is common and treatable

Symptoms in children

• Collagenous colitis is rare in children, so similar symptoms usually have another cause that a doctor will check for
• Watery diarrhoea that keeps coming back
• Tummy pain and bloating
• Poor appetite, weight loss, or slower growth than expected
• Tiredness or low energy
• Any child with ongoing diarrhoea, weight loss, or slowed growth should be seen by a doctor

Symptoms in older adults

• Diarrhoea may lead to dehydration more quickly, causing dizziness, confusion, or unsteadiness on the feet
• Tiredness and weakness can be more noticeable, and may raise the risk of falls
• Accidental leakage of stool can be more of a problem and can affect confidence and going out
• Many older adults take several medicines, some of which can trigger or worsen the condition, so a medicine review with a doctor or pharmacist is worth asking for
• Loss of appetite and weight loss should always be checked by a doctor

Causes

Main causes

• The exact cause is not fully known. It is thought to be linked to an abnormal reaction of the immune system in the lining of the bowel.
• Inflammation in the bowel lining leads to a build-up of a protein called collagen just beneath the surface, which is where the name comes from.
• Some medicines are linked to triggering it or making it worse — for example some painkillers of the anti-inflammatory type, some stomach-acid medicines, some antidepressants, and some antibiotics. Never stop a prescribed medicine on your own; ask your doctor or pharmacist first.
• Some cases appear to start after a bout of infection in the bowel, or after a period of stress.
• Some people have problems reabsorbing bile acids (fluids made by the liver to help digest fat) in the lower bowel, which can cause watery diarrhoea.
• Smoking seems to be linked to a higher chance of getting it and to more flare-ups.

Risk factors

• Being over 50 years old
• Being a woman
• Taking certain medicines long-term, particularly some anti-inflammatory painkillers and some stomach-acid medicines
• Having another autoimmune condition, such as an underactive thyroid, coeliac disease, type 1 diabetes, or rheumatoid arthritis
• Smoking
• A recent infection in the bowel
• Long-term stress, which can make symptoms worse even if it is not the direct cause

When to see a doctor

See a doctor urgently if:

• Diarrhoea lasting more than a week, or that is getting worse
• Any blood in your stool, or black tarry stools
• Signs of dehydration — dry mouth, very dark urine, dizziness on standing, feeling very tired and weak
• Losing weight without trying
• Severe tummy pain, or pain with a high temperature
• Accidental leakage of stool that affects your daily life

Book a routine appointment if:

• Watery diarrhoea that keeps coming back over weeks or months
• Ongoing bloating, wind, or tummy cramps
• Loose stools that have changed your daily routine or made you avoid going out
• Tiredness that does not improve with rest
• You want to review whether any of your regular medicines could be playing a part

Diagnosis

There is no single blood test for collagenous colitis. The key step is usually a bowel camera test (colonoscopy or a shorter test called flexible sigmoidoscopy) where the doctor takes small tissue samples, called biopsies, from the lining of the bowel. These are checked under a microscope, which is the only way to confirm the thickened collagen band. Because the bowel looks normal to the eye, the diagnosis can be missed if biopsies are not taken. Your doctor will also do tests to rule out other causes of watery diarrhoea, such as infections, coeliac disease, and thyroid problems.

Tests that may be done

• Stool (poo) tests to check for infection and to look for signs of inflammation
• Blood tests to check your blood count, iron levels, vitamin levels, thyroid, and coeliac disease
• Colonoscopy or flexible sigmoidoscopy — a thin flexible tube with a camera is passed into the back passage to look at the bowel
• Biopsies — small painless tissue samples taken during the camera test and checked under a microscope
• Sometimes a scan of the tummy, or a test of how well your bowel handles bile acids
• A review of all your medicines to spot possible triggers

What to expect at your appointment

The camera test is usually done as a day case. You will be given medicine to make you comfortable and drowsy, or in some cases a light sedative, and it usually takes 20 to 45 minutes. You may have some wind and bloating afterwards. The biopsy results usually take one to two weeks, because the tissue needs to be specially prepared before it can be looked at under a microscope. Waiting for results can feel unsettling, so it can help to ask when to expect them and who will contact you.

Treatment

Collagenous colitis can usually be well controlled, although it may come and go over time. Treatment is tailored to you and works in steps: first, your doctor will look at whether any of your medicines could be triggering it; then simple self-care and dietary changes; and if symptoms continue, specific treatments can be tried. The aim is to firm up your stools, reduce how often you need the toilet, and get you back to normal life.

Self-care at home

• Drink plenty of fluids through the day — water is best — to replace what you lose with diarrhoea
• Eat smaller meals more often rather than large heavy ones
• Cut down on caffeine, alcohol, fizzy drinks, and very fatty or very spicy foods if they seem to make things worse
• Keep a simple food and symptom diary for a few weeks to spot patterns
• Ask your doctor or pharmacist to review your medicines — but never stop a prescribed medicine by yourself
• Plan ahead when you go out: know where the toilets are, and carry spare underwear and wipes if that helps you feel confident
• Try to manage stress — gentle relaxation, breathing exercises, or a walk can help symptoms and how you feel about them
• Do not smoke, and ask for help to stop if you do

Medical treatments

Treatments are chosen step by step. Your doctor will first review your medicines with you and consider stopping or swapping anything that might be contributing. Dietary changes, often with the help of a dietitian, can help some people. Anti-diarrhoeal medicines can reduce how often you need the toilet. Other options include medicines that bind bile acids in the bowel, a course of a steroid-type medicine that works mainly inside the bowel with fewer whole-body effects, and, for people who do not respond, medicines that calm the immune system. All of these need to be prescribed and monitored by a doctor, who will discuss the benefits and possible side effects with you. Treatment is usually given for a set period and then reviewed.

When is surgery considered?

Surgery is very rarely needed for collagenous colitis. It is only considered in the small number of people who have severe symptoms that do not respond to any other treatment over a long period, and whose quality of life is badly affected. If it is ever discussed, it would mean removing part or all of the large bowel, and a specialist team would explain the operation, the risks, and what life would be like afterwards in detail.

Living with this condition

Most people with collagenous colitis carry on with work, family life and hobbies. The main day-to-day challenge is managing the unpredictability of diarrhoea and urgency. Learning your triggers, knowing your treatment plan, and planning ahead for toilets and spare clothes can make a big difference to your confidence. Symptoms often settle with treatment, and many people have long stretches with few or no problems, with occasional flare-ups that can be treated again.

Lifestyle tips

• Keep a food and symptom diary so you and your dietitian can spot triggers
• Eat regular, balanced meals and stay well hydrated
• Limit alcohol and caffeine, which can loosen stools
• Ask about a referral to a dietitian for personalised advice
• Build gentle activity into your week — walking, swimming, or anything you enjoy
• Protect your sleep, since poor sleep can worsen how you feel about your symptoms
• Review your medicines regularly with your doctor or pharmacist
• Tell your employer if you need easier access to a toilet — many workplaces can make simple adjustments

Diet and exercise

There is no single diet that works for everyone with collagenous colitis. Some people find that reducing caffeine, alcohol, and very fatty or spicy foods helps. Others benefit from a structured diet guided by a dietitian, such as a short trial of a low-FODMAP plan (a way of eating that cuts down on certain sugars that are hard to digest) followed by careful reintroduction of foods, so you do not miss out on important nutrients. Do not cut out food groups on your own for long periods. Gentle regular exercise, such as walking or swimming, can help your digestion, your mood and your sleep. If you feel tired, build up slowly and drink enough fluids.

Mental health and emotional wellbeing

It is very common to feel embarrassed, worried, or fed up when you have ongoing diarrhoea. Many people start avoiding social events, travel, or even leaving the house because they are anxious about finding a toilet. That anxiety is a real part of the condition, not a weakness, and it usually improves as symptoms come under control. Tell your doctor how it is affecting you — help is available, including talking therapies, and it is worth asking about them. If you ever feel hopeless or have thoughts of harming yourself, please reach out straight away: contact your local crisis line or emergency services, or speak to a trusted person who can help you get support. You do not have to cope alone.

Prevention

There is no proven way to prevent collagenous colitis, because the exact cause is not fully understood. Some things may lower your chances or help keep symptoms calmer: not smoking, having your medicines reviewed regularly so you are only taking what you need, and getting good treatment for any other conditions you have, such as thyroid problems. If you have already been diagnosed, sticking with your treatment plan and knowing your triggers can help reduce flare-ups.

Vaccines

There is no vaccine for collagenous colitis. However, keeping up to date with routine vaccinations recommended in your country is sensible, especially if you are ever prescribed medicines that dampen the immune system — in that case your doctor may advise on additional vaccines. Ask your doctor or pharmacist what is right for you.

Screening programmes

There is no national screening programme for collagenous colitis. It is found by testing when symptoms are present. If you have ongoing watery diarrhoea, your doctor may also check for other conditions that can run alongside it, such as coeliac disease or thyroid problems, using simple blood tests.

Complications

If left untreated

• Dehydration and loss of body salts, which can cause tiredness, dizziness, cramps, and confusion
• Weight loss and poor nutrition if diarrhoea goes on for a long time
• Thinner bones (osteoporosis) in some people, particularly if steroid-type medicines are needed for long periods or if nutrients are poorly absorbed
• Accidental leakage of stool, which can affect confidence and daily life
• Low mood, anxiety, and isolation linked to embarrassing symptoms
• Rarely, more severe bowel problems — but this is uncommon and collagenous colitis does not turn into cancer

Long-term outlook

The outlook is generally good. Collagenous colitis is a long-term condition for many people, and it can flare up and settle down over the years, but it is treatable and most people get good control of their symptoms. Some people find it settles on its own over time. It does not damage the bowel permanently and it does not increase your risk of bowel cancer. With the right support from your doctor, a plan that works for you, and attention to fluids and nutrition, most people are able to get back to the things they enjoy.

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