Introduction

Crohn's disease is a long-term condition that causes inflammation of the lining of the digestive system.

Inflammation can affect any part of the digestive system, from the mouth to the back passage, but most commonly occurs in the last section of the small intestine (ileum) or the large intestine (colon).

Commonsymptoms caninclude:

• Traveller's diarrhoea
• abdominal pain
• fatigue (extreme tiredness)
• unintended weight loss
• blood and mucus in your faeces (stools)

People with Crohn's disease sometimes go for long periodswithout symptoms or with very mild symptoms. This is known as remission. Remission can be followed by periods where symptoms flare up and become particularly troublesome.

However, research suggests a combination of factors may be responsible.These include:

• genetics genes you inherit from your parents may increase your risk of developing Crohn's disease
• the immune system the inflammation may be caused by a problem withthe immune system (the body's defence against infection and illness) that causes it toattack healthy bacteria in the gut
• previous infection a previous infection may trigger an abnormal response from the immune system
• smoking smokers with Crohn's disease usually have more severe symptoms than non-smokers
• environmental factors Crohn's disease is most common in westernised countries such as the UK, and least common in poorer parts of the world such as Africa, which suggests the environment has a part to play (known as the hygiene hypothesis)

Ifthis doesn'thelp, medication to suppress the immune system (immunosuppressants) and medication to reduce inflammation may be used.

Insome cases, surgerymay be needed to removethe inflamed section of intestine.

Once your symptoms are under control (in remission), further medication may be needed to help maintain this.

Who is affected?

Crohn's disease is a relativelyuncommon condition. There are currently at least 115,000 people living with the condition in the UK.

Crohn's diseasecan affect people of all ages, including children. However, most cases first develop between the ages of 16 and 30.

A large number of casesalso develop between theages of60 and 80.

It affects slightly more women than men, but in children more boys are affected than girls.

The conditionis more common in white people than in black or Asian people. It's most prevalent among Jewish people of European descent.

These problems usually require surgical treatment.

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.

Find out more about the register .