Appendicitis is a painful swelling of the appendix, a finger-like pouch connected to the large intestine.
Appendicitis typically starts with a pain in the middle of your abdomen (tummy) that may come and go. Within hours the pain travels to the lower right-hand side, where the appendix usually lies, and becomes constant and severe.
Pressing on this area, coughing or walking, may all make the pain worse. You may lose your appetite, feel sick and occasionally experience diarrhoea.
Read more about the symptoms of appendicitis.
When to get medical help
If you're experiencing abdominal pain that's gradually getting worse, contact your GP or local out-of-hours service immediately. If these options aren't available, call NHS 111 for advice.
You should call 999 for an ambulance if you have pain that suddenly becomes and continues to get worse and spreads across your abdomen. These are signs that your appendix may have burst, which can lead to potentially life-threatening complications.
Read more about diagnosing appendicitis and the complications of appendicitis.
How appendicitis is treated
In most cases of appendicitis, the appendix will need to be surgically removed as soon as possible. Removal of the appendix, known as an appendectomy or appendicectomy, is one of the most common operations in the UK and its success rate is excellent.
The operation is most commonly performed as 'keyhole' surgery (laparoscopy), which involves making several small cuts in your abdomen, through which special surgical instruments are inserted. 'Open' surgery, where a single larger cut is made in the abdomen, is usually carried out if the appendix has burst or access is more difficult.
Most people make a full recovery from an appendectomy in a couple of weeks, although strenuous activities may need to be avoided for up to six weeks after open surgery.
Read more about treating appendicitis.
What causes appendicitis?
It's not exactly clear what the causes of appendicitis are, although most cases are thought to occur when something, usually a small piece of faeces (stool) or a swollen lymph node within the wall of the bowel (often following an upper respiratory tract infection), blocks the entrance of the appendix.
This obstruction leads to the development of inflammation and swelling. The pressure caused by the swelling can then lead to the appendix bursting.
As the causes are not fully understood, there's no guaranteed way of preventing appendicitis.
Who is affected
Appendicitis is a common condition. Around 40,000 people are admitted to hospital with appendicitis each year in England and it's estimated that around one in every 13 people will develop it at some point in their life.
Appendicitis can develop at any age, but it is most common in young people from 10 to 20 years old.