Merck Manual

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Quick Facts



The Manual's Editorial Staff

Last full review/revision Aug 2019
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What is appendicitis?

Your appendix is a small finger-shaped hollow tube on the end of your large intestine. Appendicitis is an inflammation that causes your appendix to swell and become infected.

  • Appendicitis is a common problem

  • Common symptoms are belly pain, feeling sick to your stomach, and fever

  • Doctors treat appendicitis with surgery and antibiotics

If appendicitis isn't treated, your appendix can burst (rupture). This causes an infection in your belly called peritonitis. Peritonitis can be life-threatening.

What causes appendicitis?

Appendicitis is usually caused when something, such as a tiny piece of hard stool (poop), blocks your appendix. The blockage causes infection and swelling.

What are the symptoms of appendicitis?

Symptoms of appendicitis include:

  • Pain that starts in the middle part of your upper belly area and shifts to your right lower belly

  • Pain that gradually gets worse over a day or two

  • More pain when you move or cough or when someone presses on the sore spot

  • Loss of appetite

  • Feeling sick to your stomach and throwing up

  • Sometimes fever of 100° to 101° F (37.7° to 38.3° C)

In many people and in babies and children:

  • Pain may be all over the belly, not just the lower right

In older people and in pregnant women:

  • Pain may be less severe and the belly area less tender

If your appendix bursts:

  • You may have less pain for several hours

  • Then, pain becomes severe

  • The infection can spread inside your belly (a condition called peritonitis)

  • The infection can spread to your bloodstream causing some of your organs to stop working normally (sepsis) and your blood pressure to become dangerously low (septic shock)

How can doctors tell if I have appendicitis?

Doctors sometimes diagnose appendicitis based on your symptoms and physical examination. But usually they'll also do:

They're more likely to use ultrasound for children and a CT scan for adults.

How do doctors treat appendicitis?

Doctors treat appendicitis with:

  • Surgery to remove your appendix through either an open cut or a laparoscope

  • IV antibiotics

If your appendix has already burst at the time of surgery, you'll need to stay in the hospital and get IV antibiotics and fluids for a longer time to avoid sepsis.

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