Microscopic Colitis is a type of Inflammatory Bowel Disease. When you have Microscopic Colitis your immune system does not work properly, causing inflammation. This can lead to frequent, watery diarrhoea that keeps coming back. It can also cause tummy pain, fatigue and bloating.

Microscopic Colitis is a lifelong condition. But the right treatment can make a huge difference to your quality of life. This can help you get your condition under control, and there will be times when you have fewer symptoms or none at all. But you may also experience relapses, when your symptoms return or get worse.

As information about the condition increases, it is becoming better known and understood. More cases are being diagnosed as our understanding develops.

How does Microscopic Colitis affect the gut?

Microscopic Colitis has not been known about for as long as Crohn’s or Ulcerative Colitis.

Crohn’s can affect any part of your gut, from your mouth to your bottom. Ulcerative Colitis only affects your large bowel, which includes the colon and rectum. Microscopic Colitis only affects the colon.

With Ulcerative Colitis, doctors may use a camera on a long flexible tube, called an endoscope, to look at the lining of the large bowel. The doctor will be able to see the inflammation on the lining of the large bowel. But with Microscopic Colitis, your colon will usually look healthy when looked at through a endoscope. The doctor will need to take samples, called biopsies, of the colon and look at them under a microscope to see the inflammation that Microscopic Colitis causes.

Microscopic Colitis carries less risk of serious complications than Ulcerative Colitis or Crohn's. But it is a serious condition that can have a huge effect on quality of life.

The main symptom of Microscopic Colitis is ongoing watery diarrhoea. Diarrhoea is the passing of watery or loose poo more than three times a day for longer than four weeks. For some people, this can be as many as 15 times during the day and night. It can begin suddenly or gradually, and can get worse over time.

With Microscopic Colitis, the diarrhoea:

• May be sudden – you may not always reach the toilet in time
• May happen several times a day and at night
• Is less likely to have blood in it than if you have Crohn’s and Ulcerative Colitis

When you have diarrhoea, your body loses a lot of fluid. It is important to drink plenty of fluids to avoid getting dehydrated. Find out more in our information about diarrhoea and dehydration.

Other symptoms can include:

• Pain in the tummy area, which may be cramping or dull.
• Fatigue or extreme tiredness. This could be from getting up at night to go to the toilet, but many people experience this even if they sleep through the night.
• Joint pain.
• Bloating and wind.
• Weight loss.

We do not know what causes Microscopic Colitis. It may be caused by different factors.

These factors include:

• Damage to the lining of the gut – this may be caused by viruses, bacteria or certain medicines.
• Your immune system not working properly and affecting the gut microbiome. The microbiome is the natural bacteria, fungi and viruses that live in your gut.
• Your genes – studies suggest that genes play an important role in Microscopic Colitis.

Microscopic Colitis can affect anyone, from any background, age, ethnicity or sex. But there are some risk factors that may mean you are more likely to get it. These factors include:

• Most people are diagnosed with Microscopic Colitis when they are aged around 60 years. But around 1 in every 4 people (25%) are under 45. Children have also been diagnosed with the condition, although this is rare.
• The risk of developing Microscopic Colitis is higher in women than men.
• Having an autoimmune disease – see the section on autoimmune conditions.
• Smoking cigarettes.
• Use certain medicines – see the section changes to your lifestyle that can help.

Around 1 in every 2,000 people are thought to have Microscopic Colitis in the UK. But the real number could be a lot higher. This is because the condition may be underreported and misdiagnosed.

Autoimmune conditions

Microscopic Colitis has been linked to some other autoimmune conditions. An autoimmune condition is caused by the immune system attacking other parts of the body.

Around 4 in 10 people with Microscopic Colitis also have an autoimmune condition.

These may include:

• Type 1 diabetes
• Thyroid disease
• Rheumatoid arthritis.

Having these conditions makes it more likely that you will have Microscopic Colitis as well.

Coeliac disease

Another autoimmune condition closely associated with Microscopic Colitis is coeliac disease. This is a condition that causes your immune system to attack your gut when you eat gluten. Gluten is a type of protein found in wheat, barley and rye.

Both conditions affect the production of white blood cells and have similar symptoms. These can include diarrhoea, bloating and tummy pain. This means Microscopic Colitis can sometimes be misdiagnosed as coeliac disease.

You can have both conditions together. You are more likely to have Microscopic Colitis if you already have coeliac disease. If you do have both, you may still have diarrhoea on a gluten-free diet if your Microscopic Colitis is not treated.

Irritable bowel syndrome (IBS)

IBS is a common, lifelong condition affecting the digestive system. Many of its symptoms are very similar to the symptoms of Microscopic Colitis. These include diarrhoea, tummy pain and bloating. The exact cause of IBS is not known, and there is no cure. But medicines and careful changes to diet can usually help keep the symptoms under control.

Microscopic Colitis is sometimes misdiagnosed as IBS. This is because their symptoms are so similar, and IBS is more well known in comparison. Some people may have both conditions at the same time. Around 1 in 10 people with IBS involving diarrhoea may also have Microscopic Colitis. This can make diagnosis difficult. This means that sometimes people do not receive the correct diagnosis and treatment as quickly as they should.

Crohn’s and Ulcerative Colitis

Some evidence suggests that Microscopic Colitis may sometimes develop into Crohn’s or Ulcerative Colitis. At the moment, we do not understand how this happens, but the risk of this happening is small.

Bile acid malabsorption (BAM)

Around 4 out of 10 people with Microscopic Colitis also have BAM. This is when bile acids used in digestion cannot be reabsorbed as usual and cause bile acid diarrhoea (BAD).

BAM is treated with bile acid binders. These medicines work by binding to the bile acids in your gut. This stops them from reaching the colon so that they cannot cause diarrhoea. You may be offered bile acid binders if your Microscopic Colitis is related to BAM. You may also be offered bile acid binders if other treatments do not stop your diarrhoea. 

If your healthcare professional thinks your Microscopic Colitis is related to BAM, you may be sent for a special test called a SeHCAT scan.

There is more on SeHCAT scans in the section how is it diagnosed? Find out more about BAM in other treatments. Find out more about diarrhoea, including how to manage it, in our information on diarrhoea.

Microscopic Colitis and risk of colon cancer

Microscopic Colitis does not make you any more likely to get colon cancer than the general population.

Talk to your GP if you think your symptoms could be caused by Microscopic Colitis. Your GP will need to take a history of all your symptoms. This may help them rule out other conditions.

Poo tests, known as faecal calprotectin tests, are often used to help diagnose Crohn’s and Colitis. This test may not be useful for Microscopic Colitis. In Microscopic Colitis, calprotectin levels are often normal or only slightly raised.

If your GP thinks you may have Microscopic Colitis, you will need to be referred for a colonoscopy and a biopsy. You may also need to be tested for other autoimmune conditions, such as coeliac disease.

It may take time to diagnose Microscopic Colitis. This is because the condition is not always as well-recognised as other forms of Inflammatory Bowel Disease.

See our appointment guide for information on getting the most out of your appointments. This includes tips about talking to your healthcare professional.

In Microscopic Colitis, signs of inflammation can only be seen under a microscope. You will need to have a colonoscopy so that a tissue sample, or biopsy, can be taken.  

During a colonoscopy, a long flexible tube is inserted through your bottom. The tube is about the thickness of your little finger, with a bright light and camera at its tip,  This lets the doctor look at the lining of your colon. During the procedure, a biopsy is taken from your colon. This is then looked at under a microscope.  

Most colonoscopies are performed under mild sedation. This is when you are given medicine through a tube in your arm to make you feel relaxed. You may be offered gas and air or painkillers instead, to make you more comfortable.

There are several changes to your lifestyle that may improve your symptoms. Your healthcare professional may suggest:

• Stopping taking certain specific medicines for other conditions and switching to another
• Making changes to your diet
• Stopping smoking, if you currently smoke
• Exercising more

Stopping medicines that can make Microscopic Colitis symptoms worse

Before offering any treatment for Microscopic Colitis, your doctor will check if you take any medicines for other conditions.

Medicines that may make your Microscopic Colitis symptoms worse include:   

• Non-steroidal anti-inflammatory drugs, known as NSAIDs. These include aspirin, ibuprofen or diclofenac
• Certain medicines used to reduce stomach acid, known as proton pump inhibitors, or PPIs. These include omeprazole and lansoprazole.
• Certain medicines to reduce indigestion and heartburn, such as histamine-2 antagonists. This includes famotidine.^.
• Certain medicines used to treat depression, such as selective serotonin reuptake inhibitors (SSRIs). These include citalopram, fluoxetine, sertraline,
• Acarbose, for type 2 diabetes.
• Ticlopidine, for blood conditions.
• Statins, for cholesterol control, such as simvastatin or atorvastatin.

Many of these medicines can also cause diarrhoea as a side effect. You can read more about some of these medicines in our information on other treatments.

Always talk to your doctor before stopping or changing any medicines you are taking.

Changes to your diet and drinking habits

Making changes to your lifestyle may help to reduce your symptoms.  

• Try cutting down on caffeine. Drink decaffeinated tea, decaffeinated coffee and non-caffeinated soft drinks. Try reducing the amount of chocolate you eat - chocolate contains caffeine
• Cut down on alcohol. Drinking less has been shown to help symptoms. National guidelines recommend drinking no more than 14 units of alcohol per week, spread over at least three days. See the NHS website for more information.
• There is no evidence to suggest that specific foods affect people with Microscopic Colitis. But you may find that certain foods are a trigger for you. Everyone is different, but keeping a food diary can help you understand what foods make you more unwell. A dietitian can help you find a healthy diet that works for you. Try using the food diary in food.

Many people ask: 

• Should I avoid gluten? People with Microscopic Colitis are more likely to have coeliac disease than the general population. Having coeliac disease means you are not able to digest a type of protein called gluten, which is found in wheat, barley and rye. Talk to your GP if you think you may have coeliac disease. They can do a blood test to check. If this is positive, you may also need an endoscopy. This can help confirm your diagnosis. Find out more in food and tests and investigations.
• Should I avoid dairy products? If your diarrhoea is worse after eating dairy, you may have trouble digesting lactose. Lactose is a type of sugar found mainly in milk, cheese and other dairy products. Keeping a food diary and recording your symptoms can help you find out if this is the case for you. Sometimes, a simple breath test is used to find out if you are lactose intolerant. Speak to your GP if you think you may be lactose intolerant.

Talk to your doctor or dietitian before making any major changes to your diet. They can help you plan how to avoid certain foods while still getting the nutrients you need.

There may be several options for treatment depending on the severity of your symptoms. These include:

Loperamide

If you have mild Microscopic Colitis, medicines to stop diarrhoea, such as loperamide, can help. These make food move through the gut more slowly and allows more water to be absorbed. Poo becomes firmer and you may need to go to the toilet less urgently. They can also help to control symptoms while other medicines take time to work. Find out more in our information on diarrhoea.

Bile acid binders

Bile acid binders, such as colestyramine or colesevelam, attach to the bile acids in your gut. You may be offered this medicine if your Microscopic Colitis is related to bile acid malabsorption (BAM). It may also be offered if you continue to have diarrhoea despite other treatment. Find out more in our information on other treatments.

Budesonide

Budesonide is used to reduce inflammation to control symptoms of Microscopic Colitis. This steroid has been found to help some people who have moderate to severe Microscopic Colitis. As with all steroids this is not usually a long-term option. Find out more in our information on steroids.

Immunosuppressants

Azathioprine and mercaptopurine may help some people if budesonide has not worked. Find out more in azathioprine and mercaptopurine.

Surgery

It’s rare to need surgery if you have Microscopic Colitis. Your healthcare professional may suggest surgery if other treatments have not worked. You can find out more about possible operations in surgery for Ulcerative Colitis.

Our Helpline takes many calls from people with Microscopic Colitis, so you are not alone. We cannot advise but it may help to talk through your worries. Your doctor will support you and you should ask for support from an IBD nurse-led service.

An IBD nurse can offer support and advice about treatment options and daily life with Microscopic Colitis, and help you to live well with IBD. But NHS support services vary – unfortunately some hospital IBD teams do not treat Microscopic Colitis. And some areas still do not have an IBD nurse, while others have limited resources and may not be able to support you if you have Microscopic Colitis.

Find out if your hospital has an IBD nurse.

Our Helpline team can provide information and support to anyone affected by Inflammatory Bowel Disease. You can find more information, including contact details, below and on the Helpline webpage.