The appendix is a small, pouch-like organ in the lower right side of your abdomen. For years, experts thought it had no real function, but newer research suggests it may help restore healthy gut bacteria after diarrhea or antibiotic use.

Despite being small, problems with the appendix can become dangerous. Appendicitis, an infection of the appendix, is a medical emergency because the organ can burst and lead to life-threatening complications.

What Does the Appendix Do?

Scientists continue to debate the appendix’s purpose:

  • Vestigial theory: Some believe it’s a leftover organ from our evolutionary past, with little to no current function.

  • Immune role: In other mammals, the appendix helps regulate immune cells during infections, which may also be true in humans.

  • Gut health reservoir: Recent studies suggest it stores “good” bacteria to help rebalance the gut microbiome after illness or antibiotics.

While you can live without it, the appendix may play a small but supportive role in digestive and immune health.

Where Is the Appendix Located?

The appendix is a finger-like pouch about 3–4 inches long, attached to the top of the large intestine where it meets the small intestine.

  • Location: Lower right-hand side of the abdomen

  • Pain pattern: Problems usually start with pain near the belly button that moves to the lower-right abdomen

Signs Something Is Wrong with Your Appendix

The most common appendix issue is appendicitis, when the organ becomes blocked and inflamed.

Symptoms of Appendicitis:

  • Pain starting near the belly button, shifting to the lower-right abdomen

  • Pain that worsens with coughing, sneezing, or movement

  • Loss of appetite

  • Nausea or vomiting

  • Fever

  • Abdominal swelling

If untreated, the appendix can burst, spreading infection throughout the abdomen (peritonitis).

Other Appendix-Related Conditions

Although less common than appendicitis, other appendix issues include:

Appendix Cancer

Rare, but possible. Symptoms appear only when tumors grow larger:

  • Bloating

  • Pain or fullness after small meals

  • Nausea or vomiting

Carcinoid tumors, the most common appendix cancer, can release hormones that cause carcinoid syndrome:

  • Flushing

  • Diarrhea

  • Wheezing

  • Heart valve problems

Conditions Often Mistaken for Appendicitis

Abdominal pain isn’t always appendicitis. Other conditions with similar symptoms include:

  • Ovarian cysts – Sudden, sharp pelvic pain when ruptured

  • Crohn’s disease – Chronic inflammation of the intestines

  • Pelvic inflammatory disease (PID) – Bacterial infection causing abdominal pain

  • Kidney stones – Sharp, intense pain from urinary tract blockage

  • Infections – Such as yersiniosis, linked to undercooked pork, causing lower-right abdominal pain

When To Seek Medical Care

Seek urgent medical help if you experience:

  • Sudden, severe abdominal pain (especially in the lower right)

  • Pain with nausea, vomiting, or fever

  • Abdominal swelling

  • Unexplained loss of appetite

Appendicitis is a medical emergency. If untreated, a burst appendix can lead to severe infection and even death.

Diagnosis and Treatment

How It’s Diagnosed

Doctors may use:

  • Physical exam (checking abdominal tenderness)

  • Blood and urine tests (to detect infection or rule out other causes)

  • Imaging scans (ultrasound, CT, or MRI)

How It’s Treated

  • Appendicitis: Surgery (appendectomy) is the standard treatment, sometimes preceded by antibiotics.

  • Appendix tumors: Surgery and possibly chemotherapy, depending on cancer type and stage.

  • Other conditions: Treatments vary based on the underlying issue.

A Quick Review

The appendix is a small organ in the lower right abdomen. While its function remains debated, research suggests it may help maintain healthy gut bacteria. The most common problem is appendicitis, marked by sharp abdominal pain that shifts from the belly button to the lower right.

Because appendicitis can lead to a ruptured appendix and life-threatening infection, any severe or unusual abdominal pain should be evaluated immediately.