Diverticulitis and appendicitis can feel alike at first. Both cause belly pain, fever, and nausea, and both can become serious. But they involve different parts of the colon and usually cause pain on different sides, and both need prompt attention. Here is how to tell them apart and why getting checked quickly matters.
The Main Difference
Appendicitis is inflammation of the appendix, a small pouch at the start of the colon on the lower right side. Diverticulitis is inflammation of small pouches in the colon, most often on the lower left side. The side the pain settles on is the single biggest clue.
Appendicitis in Brief
Appendicitis often starts with vague pain near the belly button that then moves to the lower right belly and becomes sharp and steady. It usually builds over hours, with nausea, loss of appetite, and a low fever. Appendicitis is a surgical emergency, because an inflamed appendix can burst.
Diverticulitis in Brief
Diverticulitis usually causes pain in the lower left belly that can come on over a day or two, along with fever, nausea, and a change in bowel habits. It is more common after age 40. See the difference between the pouches and the flare in our diverticulosis vs diverticulitis guide.
How to Tell Them Apart
- Side of pain: appendicitis is usually lower right, diverticulitis usually lower left.
- How it starts: appendicitis often starts near the navel and migrates to the right, diverticulitis tends to stay on the left.
- Age: appendicitis is more common in younger people, diverticulitis more common after 40.
- Speed: appendicitis often builds over hours, diverticulitis over a day or two.
These are general patterns, and they are not reliable enough to diagnose at home, which is why belly pain with fever should be evaluated promptly.
How They Are Diagnosed
Both are usually confirmed with a CT scan, along with blood tests to check for infection. The scan shows which organ is inflamed and how severe it is, which guides treatment.
When to Seek Care
Go to the emergency room for severe or worsening belly pain, especially with fever, or for lower right belly pain that is getting worse, since appendicitis needs urgent surgery. Diverticulitis also needs prompt treatment. After a diverticulitis attack settles, a colonoscopy is often recommended to check the colon.
Talk to a Gastroenterologist in Mountainside, NJ
If your symptoms keep coming back or you are not sure what is causing them, Dr. Amber Khan can help. We see patients from across Union County and New Jersey.