Inflammatory bowel disease (IBD) is a term mainly used to describe two conditions, ulcerative colitis and Crohn's disease.

Both ulcerative colitis and Crohn’s disease are long-term (chronic) conditions that involve inflammation of the gut (gastrointestinal tract).

Ulcerative colitis only affects the colon (large intestine), while Crohn’s disease can affect all of the digestive system, from the mouth to the anus.

It’s sometimes difficult to tell the difference between the two main types of IBD. If this is the case, it’s known as indeterminate colitis.

There are other, less common types of IBD called collagenous colitis and lymphocytic colitis. The inflammation can only be seen using a microscope, and so they’re known as microscopic colitis.

What are the symptoms?

The main symptoms of ulcerative colitis and Crohn’s disease are similar. They include:

• pain, swelling or cramping in the tummy
• recurring or bloody diarrhoea
• weight loss
• extreme tiredness

Not everyone has all of these symptoms, and some people may experience additional symptoms, including vomiting, anaemia and high temperature (fever).

The symptoms of IBD can come and go. People may experience periods of severe symptoms (flare-ups), and go through long periods when they have few or no symptoms at all (remission).

Read more about the symptoms of ulcerative colitis and symptoms of Crohn’s disease.

Causes of inflammatory bowel disease

The exact causes of ulcerative colitis and Crohn’s disease are unclear. It’s thought that several factors may play a part, such as:

• genetics – there is evidence that you are more likely to develop IBD if you have a close relative with the condition
• disruption to the immune system (the body’s defence against infection) – inflammation may be caused by the immune system attacking healthy tissue inside the digestive system while fighting off a virus or bacteria

Read more about the causes of ulcerative colitis and causes of Crohn’s disease.

Treatment of IBD

There is currently no cure for ulcerative colitis or Crohn's disease. Treatment aims to relieve symptoms and prevent them from returning.

Mild ulcerative colitis may not need treatment as symptoms can clear up after a few days.

Medicines used to treat ulcerative colitis or Crohn's disease include:

• aminosalicylates, or in more severe cases, corticosteroids – to reduce inflammation
• immunosuppressants – to reduce the activity of the immune system

An estimated 20% of people with ulcerative colitis have severe symptoms that often don't respond to medication. In these cases, it may be necessary to surgically remove an inflamed section of the digestive system.

Around 60-75% of people with Crohn’s disease will require surgery to repair damage to their digestive system and treat complications of the condition. Read more about treating ulcerative colitis and treating Crohn’s disease.

Who is affected?

It is estimated that IBD affects about one person in every 250 in the UK. There are around 146,000 people with ulcerative colitis and 115,000 with Crohn's disease in the UK.

IBD is usually diagnosed in people in their late teens or early 20s, but can affect people of any age.

IBD is more common in white people than in black people or those of Asian origin. People from an Eastern European Jewish background are most likely to be affected by IBD.

Woman and men are equally affected.

Want to know more?

• Crohn's and Colitis UK: Inflammatory Bowel Disease
• Core: What is Crohn’s disease? (PDF, 145kb)
• Core: What is ulcerative colitis? (PDF, 107kb)

Irritable bowel syndrome (IBS)

IBD is not the same as irritable bowel syndrome (IBS), which is a common condition that causes symptoms such as:

• constipation
• diarrhoea
• abdominal pain