Overview
A Helicobacter pylori infection is a common stomach infection. It's caused by a germ called Helicobacter pylori, a bacteria also known as H. pylori.
More than half the people in the world may have an H. pylori infection at some point in their lives. These infections often happen during childhood, especially in developing countries. H. pylori germs seem to spread through contact with an infected person's bodily fluids, including vomit, stool or saliva. This includes contact that happens through poor hand hygiene. The germs also can spread through tainted food and water.
H. pylori infections can cause stomach pain, bloating, gas and other symptoms. But most people who become infected don't have symptoms. Sometimes, H. pylori infections lead to sores called peptic ulcers in the lining of the stomach or small intestine. Much less often, these infections can lead to stomach cancer.
Your healthcare professional likely will test you for an H. pylori infection if you get symptoms of a peptic ulcer. Treatment for the infection includes medicines called antibiotics to clear up the bacteria.
Help prevent an H. pylori infection by not sharing food or utensils.
Symptoms
Most H. pylori infections don't cause symptoms. When a person gets symptoms, they often come from swelling of the stomach lining or a peptic ulcer. The symptoms can include:
- An ache or burning pain in the stomach area, also called the abdomen.
- Stomach pain that may feel worse when the stomach is empty.
- Upset stomach.
- Loss of appetite.
- Frequent burping.
- Bloating.
- Weight loss.
When to see a doctor
Make an appointment with your healthcare professional if you have ongoing stomach pain or other stomach symptoms. Get medical help right away for:
- Sharp, sudden or very bad stomach pain that doesn't get better.
- Bloody or black, tarry stools.
- Bloody or black vomit or vomit that looks like coffee grounds.
- Trouble swallowing.
- Unusual tiredness, dizziness or passing out.
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Causes
H. pylori infections are caused by H. pylori germs that get into the stomach lining. The germs appear to be passed from person to person through contact with saliva, vomit or stool. They also may be spread through contaminated surfaces, or tainted food or water.
Risk factors
Risk factors for H. pylori infections include your living conditions, health history and eating habits. These risk factors include:
- Living in crowded conditions. Living in a home with many other people can raise your risk of an H. pylori infection.
- Lacking a reliable supply of clean water. H. pylori germs can spread through tainted water that hasn't been treated enough for safety.
- Living in a developing country. H. pylori infections are more common in developing nations, where clean water and living conditions may be harder to access. In developing countries, these infections are more common during childhood.
- Having certain health conditions. Ongoing swelling and thinning of the stomach lining called atrophic gastritis can raise the risk of an H. pylori infection. So can an immune system condition called pernicious anemia and tumors of the stomach that aren't cancer called gastric adenomas.
- Having a family history of certain conditions. Your risk of an H. pylori infection rises if a parent or sibling has had peptic ulcers or stomach cancer.
- Sharing food or utensils. H. pylori germs can spread through saliva. So don't share food or silverware with family members or friends.
Complications
An H. pylori infection can lead to other health conditions called complications. These can include:
- Ulcers. H. pylori can damage the protective lining of the stomach and small intestine. This lets stomach acid create an open sore called an ulcer. About 10% to 15% of people with H. pylori get an ulcer.
- Swelling, also called inflammation, of the stomach lining. H. pylori infections can affect the stomach, causing irritation and swelling called gastritis.
- Stomach cancer. H. pylori infection is a strong risk factor for certain types of stomach cancer. But only a small number of people with H. pylori infections go on to get stomach cancer. Limiting salt and pickled foods may help lower the risk of cancer if you have an H. pylori infection.

Ulcers
A peptic ulcer is a sore on the lining of the stomach, small intestine or esophagus. A peptic ulcer in the stomach is called a gastric ulcer. A duodenal ulcer is a peptic ulcer that forms in the first part of the small intestine, called the duodenum. An esophageal ulcer forms in the lower part of the esophagus.
Prevention
You may be able to help prevent an H. pylori infection by not sharing food or utensils with family or friends.