Merck Manual

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Quick Facts



The Manual's Editorial Staff

Last full review/revision Mar 2021| Content last modified Mar 2021
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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:

How can doctors tell if I have appendicitis?

How do doctors treat appendicitis?

Doctors treat appendicitis with:

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

  • Give antibiotics directly into a vein (IV)

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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