Resource for patients published today by the national charity Guts UK highlights the growing number of microscopic colitis cases in the UK.
The charity has raised concerns about the number of people suffering from a misdiagnosis or living with undiagnosed and debilitating symptoms.
17,000 new cases are being diagnosed each year, but the real number could be a lot higher.
Experts have raised concerns about the number of people suffering with undiagnosed microscopic colitis, a debilitating bowel condition thought to affect thousands of adults in the UK. The national charity Guts UK has published a resource for patients during Microscopic Colitis Awareness Week to raise awareness of the disease and is calling for more research into prevention, faster diagnoses and developments in treatments.
Microscopic colitis is an inflammation of the large intestine (bowel) that causes persistent, frequent and watery diarrhoea (throughout the day and night), stomach pain, fatigue, faecal incontinence and weight loss. It is frequently misdiagnosed and the prevalence of the condition is higher than previously thought. 
Scientists estimate that around 67,000 people are living with microscopic colitis in the UK or at least 1 in 1,000 adults. 17,000 new cases are being diagnosed each year, but the real number could be a lot higher because it’s often underreported and misdiagnosed.
A 2012 study showed that one in three patients with microscopic colitis were initially incorrectly diagnosed with Irritable Bowel Syndrome (IBS) and “a large, hidden burden of undiagnosed and untreated microscopic colitis likely exists in the UK population owing to systematic misdiagnosis of microscopic colitis as IBS.”
Despite the missed diagnoses, cases of microscopic colitis are on the rise globally. The UK incidence rate of microscopic colitis in 2016 was twice that observed in 2009.
Microscopic colitis is a leading cause of diarrhoea in older adults and it can have a devastating impact on a person’s quality of life. Many people suffer with the condition for years but the correct diagnosis and treatment can make a huge difference. 
Victoria, age 33 from London, was diagnosed with microscopic colitis last year. She said:
“I spent 12 years living with undiagnosed microscopic colitis. On my worst days, I was going to the toilet 30 to 40 times per day and suffered from awful stomach cramps. I ended up becoming agoraphobic because I was so distressed. I went to the doctor again and again but it took me all these years to get a correct diagnosis. I even went to A&E but was told it was ‘just IBS’ and I was sent home with no treatment plan.
“By 2022 I became scared of eating in case it triggered symptoms and my flare ups were becoming more frequent. I felt more tired than I’d ever felt in my life and completely hopeless. I was also trying to parent my baby son while living with the condition.
“The treatment I have received after getting my diagnosis has changed my life. I feel like I’ve regained some semblance of normal.”
Microscopic colitis is named because, unlike other inflammatory bowel diseases, like Crohn’s disease or ulcerative colitis, it can’t be diagnosed with a colonoscopy alone and a sample of tissue taken from the bowel must be examined under a microscope to identify the condition. Because of this, the disease is often misdiagnosed.
Julie Harrington, CEO of Guts UK, said:
“It’s terribly sad that thousands of people are suffering with the debilitating symptoms of microscopic colitis. Most people with the condition can be easily treated with a course of gut-specific steroids or with symptom-relieving medicines but getting a diagnosis is the first, essential step.
“People living with the condition but without the benefit of a correct diagnosis and effective treatments often can often feel very isolated due to the urgent nature of their symptoms and their need to be near to toilet facilities at all times. We know that this can also have a detrimental effect on their mental wellbeing.
“The rates of microscopic colitis are increasing and are likely to grow further as the population ages, so it’s crucial that we identify risk factors, provide specific training for healthcare providers, continue to raise awareness and invest in research to improve diagnosis and treatments.”
Professor Chris Probert, Professor of Gastroenterology at the University of Liverpool said:
“Undiagnosed microscopic colitis can cause years of unnecessary suffering. The diarrhoea symptoms tend to be very severe and houselimiting leading to considerable distress for patients.
Microscopic colitis is on the increase
“It’s not clear why cases of the condition are on the increase but it is likely to be due to a mixture of increased awareness of symptoms leading to more diagnoses and environmental factors such as a potential side effect of common prescription drugs such as some antidepressants.
“The good news is that effective treatments are available so people experiencing symptoms could benefit enormously by talking with their GP.”
Resources published in March 2022 by Guts UK to raise awareness of microscopic colitis showed that women are 700% more likely than men to suffer with the condition.
Cause of microscopic colitis
The causes of microscopic colitis are still unclear. As it is a relatively new disease (first described in 1976) it has led to a presumption that it is environmental as opposed to genetic factors that are responsible for its occurrence.
About microscopic colitis:
Microscopic colitis (MC) is an inflammatory disease of the bowel that causes persistent, watery diarrhoea, usually accompanied by urgency and problems with bowel control.
Symptoms can be unrelenting and lead to a substantial loss of quality of life. 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.
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. Importantly, there are good treatments available for this condition.
Because the only way to diagnose this condition is to take a biopsy of the large bowel, as it cannot be seen by the naked eye during an endoscopy, the disease is often misdiagnosed. The faecal calprotectin test that GPs use to rule out inflammatory bowel disease cannot be used to diagnose microscopic colitis because the inflammation levels are microscopic.
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.
About Guts UK
Guts UK is the UK’s charity for the digestive system from top to tail; gut, liver and pancreas. Through strong connections with the British Society of Gastroenterology and membership of the Association of Medical Research Charities it is able to support a diverse portfolio of research work that is of the highest quality. Guts UK also provides expert information on a range of digestive conditions and symptoms for patients, and raises awareness of digestive health.