Microscopic colitis (MC) is an inflammatory disease of the bowel. It is characterised by watery diarrhoea, usually accompanied by urgency and problems with bowel control. Often people have night-time symptoms and symptoms can be unrelenting. People affected often need to identify where toilets are when they leave the house, to avoid accidents. In some cases, people are unable to leave the house at all due to the severity of their symptoms. Symptoms can be bad and lead to a substantial loss of quality of life.

Microscopic colitis can develop at any time, but it is more common in middle-age, with those affected often diagnosed between the ages of 50 and 70. It also occurs more frequently in women and can occur earlier in people who smoke. Microscopic colitis occurs in 18 people in 100,000 people, per year. Read Guts UK’s resource on microscopic colitis in women here.

Importantly, there are good treatments available for this condition. But it may not be considered as a diagnosis and therefore Guts UK hopes to raise awareness among both the public and health professionals.


It is not yet clear what causes microscopic colitis. Risk factors such as bile acid malabsorption and some medications are currently being considered.

Examples of medications that have been linked to microscopic colitis include non-steroidal anti-inflammatory drugs (such as ibuprofen and aspirin); protein pump inhibitors (such as lansoprazole); statins; some H2 antagonists (Zantac); some diabetic medications (Acarbose); some antidepressants (Sertraline); some anticoagulant medications (ticlopidine); HRT (in higher doses) and some anticonvulsants (Tegretol).

Always discuss mediations with your doctor or healthcare professional and do not stop taking any medications without their advice first.

A cell biopsy which is a tissue sample from the bowel showing collagenous colitis.

Micrograph of collagenous colitis, a type of microscopic colitis.

There are two types of microscopic colitis.

Lymphocytic colitis – this is where there are more white blood cells (lymphocytes) in the lining of the bowel. White blood cells fight infection.

Collagenous colitis – this is when the bowel lining has a thicker layer of collagen. Collagen is a protein that forms the building blocks of the bowel.

Whilst there are differences in appearance in the bowel lining when viewed with a microscope, there is no difference in symptoms or treatment.


Symptoms of microscopic colitis include:

  • Watery diarrhoea
  • Incontinence episodes
  • Waking during the night to empty the bowel
  • Urgency to use the toilet.
  • Frequent need to empty the bowel

This condition is thought to be under-diagnosed, which means people with these symptoms might have microscopic colitis that has been mistakenly identified for another condition. Most often it is misdiagnosed as IBS or diverticular disease. Figures suggest 1 in 10 people with IBS with diarrhoea may have microscopic colitis. Sadly, they may have suffered for many years prior to diagnosis when a good treatment was available. This is partly due to low awareness among some health professionals but also partly because of how the condition appears. Unlike other inflammatory bowel diseases (IBD), like Crohn’s disease or ulcerative colitis, the lining of the bowel appears normal when investigated with a colonoscope (a flexible tube with a camera at the end used to examine the inside of the bowel). Also, unlike Crohn’s disease and ulcerative colitis, the faecal calprotectin test (poo test) used to diagnose digestive tract inflammation in IBD, cannot be used to identify microscopic colitis, as results may be normal or only slightly raised. Therefore, a normal result can falsely reassure individuals that it is not microscopic colitis. But it is only when a biopsy (a small tissue sample) of the bowel is taken and examined under the microscope can the inflammation be seen.

Guts UK is keen to ensure those affected become aware of the condition, so they can discuss it with the health professionals looking after them. This is true both for those who have not been diagnosed and for those not fully settled on their current treatment. Diagnosis can be easier if more symptoms and signs are considered, in addition to the presence of watery diarrhoea. People who have microscopic colitis sometimes have other diseases of the immune system such as some thyroid problems, coeliac disease, rheumatoid arthritis, psoriasis, and diabetes. Even if they are not directly affected by an autoimmune disease, a close blood relative might be affected.


Microscopic colitis can be treated for most people. The correct diagnosis and treatment can make a huge and dramatic difference to a person’s quality of life. There is no increased risk of cancer with a diagnosis of microscopic colitis. However, there is some data suggesting that without treatment some people do need to stay in hospital as an inpatient during a flare of symptoms. We don’t want anyone suffering in silence, so Guts UK wants to raise awareness of this easily overlooked condition and put the patient in control.

Microscopic colitis can be treated with a course of gut specific steroids or with symptom-relieving medicines. Whilst these treatments work for most people, some people need further treatment or investigation. Because of this, there are ongoing studies to look at other treatment options including other drug therapies and modifying the microbiome too.

If symptoms continue then alternative diagnosis should be considered by your doctor, for example coeliac disease, lactose intolerance and bile acid diarrhoea. This strengthens the case for better diagnosis of this condition, which Guts UK hopes will happen through raising awareness among the public and health professionals.



  • Are my symptoms due to microscopic colitis?
  • Are my medicines causing my symptoms and are there any alternatives?
  • Would I benefit from a colonoscopy and a biopsy of my large bowel?
  • Do I need to be tested for other autoimmune conditions such as coeliac disease?


Read Guts UK’s resource: ‘microscopic colitis – the underdiagnosed gut condition’ here.

Microscopic colitis is a form of inflammatory bowel disease and you can find out more information from:

Crohn’s and Colitis UK (CCUK) are the UK leading charity working on Crohn’s disease and other inflammatory bowel diseases. Read their microscopic colitis information here.

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For more information on Microscopic Colitis click here. (Courtesy of Crohns & Colitis UK)