Helicobacter pylori (H. pylori) Infection

Helicobacter pylori (H. pylori) is a type of bacteria that infects the lining of the stomach. It's extremely common worldwide, and while most people with it never develop symptoms, it's a leading cause of gastritis, stomach ulcers, and — in a small percentage of long-term cases — stomach cancer.

How It Spreads

H. pylori is thought to spread through contaminated food or water, and through direct contact with saliva or other bodily fluids — often within families, especially during childhood. It's more common in areas with crowded living conditions or limited access to clean water and sanitation.

Why It Matters

Most people infected with H. pylori never know it, since it often causes no symptoms at all. But the bacteria weakens the stomach's protective lining over years, which is why it's strongly linked to peptic ulcers and chronic gastritis, and is considered a risk factor for stomach cancer with long-standing, untreated infection. Because it infects a large share of people worldwide, doctors often consider testing for it in people with ongoing dyspepsia (upper abdominal discomfort), a personal or family history of ulcers, or before starting long-term NSAID or aspirin use.

How It's Diagnosed

H. pylori can be detected through a breath test, a stool antigen test, or during an endoscopy with a tissue biopsy. Blood tests can show past exposure but aren't reliable for confirming an active infection.

Our symptoms of H. pylori and treatment for H. pylori guides cover what happens after a positive test.