H. pylori is a common type of bacteria that grows in the digestive tract and tends to attack the stomach lining. Around 44 percent of people worldwide have an H. pylori infection, according to a meta-analysis from 2018.

H. pylori infections are usually harmless, but they’re responsible for most ulcers in the stomach and small intestine.

H. pylori is adapted to live in the harsh, acidic environment of the stomach. The “H” in the name is short for Helicobacter. “Helico” means spiral, which refers to the shape of the bacteria.

This bacteria can change the environment around it and reduce the acidity so it can survive more easily. The spiral shape of H. pylori allows It to penetrate the stomach lining, where it’s protected by mucus and the body’s immune cells can’t reach it. This can lead to stomach problems.

H. pylori often infects a person’s stomach during childhood. While infections with this strain of bacteria typically don’t cause symptoms, they can lead to diseases in some people, including peptic ulcers and an inflammatory stomach condition known as gastritis.

Most people with H. pylori never have symptoms. But the bacteria can damage the inner protective lining of the stomach and cause other diseases, like a peptic ulcer. Symptoms of a peptic ulcer from H. pylori include:

  • dull or burning stomach pain (especially when you have an empty stomach)
  • bloating
  • nausea
  • unexplained weight loss
  • vomiting
  • burping
  • poor appetite

While rare, stomach cancer is also an increased risk for people with H. pylori. Stomach cancer symptoms include:

  • poor appetite
  • unexplained weight loss
  • blood in the stool
  • nausea
  • feeling full early in a meal
  • discomfort or swelling in the abdomen
  • stomach pain
  • fatigue or weakness

Still, many of the symptoms of stomach cancer, peptic ulcers, and other diseases associated with H. pylori can be caused by other issues. If you experience any symptoms you’re concerned about, talk with a doctor.

You should also get medical attention right away if you experience:

  • trouble swallowing
  • anemia
  • blood in the stool
  • black-colored feces or vomit

It’s still not known exactly how H. pylori infections spread. The bacteria has coexisted with humans for many thousands of years. The infections are thought to spread from one person’s mouth to another, like by kissing.

The bacteria may also be transferred through contact with vomit or stool. This can happen when a person does not wash their hands thoroughly after using the bathroom. H. pylori can also spread through contact with contaminated water or food.

Risk factors

Children are more likely to develop an H. pylori infection. This is largely because children may not always practice proper hygiene.

An individual’s environment and living conditions could influence their risk for an H. pylori infection. Your risk is higher if you:

  • live in a developing country
  • lack access to clean water
  • share housing with others who’ve contracted H. pylori
  • live in overcrowded conditions

If you have symptoms of a digestive condition, you may need to get tested for H. pylori. There are several ways to diagnose an H. pylori infection, including:

  • Blood test: A healthcare professional may draw a sample of blood from a person’s arm or hand. The blood sample can then be sent to a laboratory to check for antibodies to H. pylori.
  • Stool test: For this test, you’ll use a container from a healthcare professional to collect a sample of your feces. It can then be sent to a lab for either a stool antigen test or a stool culture test.
  • Breath test: A urea breath test can check for abnormal carbon dioxide levels, which can be a sign of an H. pylori infection. The test involves breathing into a collection bag twice. In between providing breath samples, you’ll consume a pill or liquid with a harmless radioactive material. A healthcare professional can then compare the two samples to see if you may have H. pylori.

A healthcare professional may recommend getting an endoscopy if the results of the other tests are inconclusive. It allows a healthcare professional to look at your esophagus, stomach lining, and a portion of your small intestine.

During the procedure, a healthcare professional will insert a long, thin tube called an endoscope into your mouth and down into your stomach and duodenum.

An attached camera will send back images on a monitor for a healthcare professional to see. The test may also involve removing a small tissue sample (biopsy) to be analyzed after the procedure.

H. pylori infections can lead to peptic ulcers, but the infection or the ulcer itself can lead to more serious complications. These include:

  • internal bleeding, which can happen when a peptic ulcer breaks through your blood vessel and is associated with iron deficiency anemia
  • obstruction, which can happen when something like a tumor blocks the food from leaving your stomach
  • perforation, which can happen when an ulcer breaks through your stomach wall
  • peritonitis, which is an infection of the peritoneum, or the lining of the abdominal cavity

H. pylori can also increase the risk of gastric adenocarcinoma, a type of stomach cancer. This risk is higher among smokers, as well as Black people/African Americans, Latinos and Hispanics, and Asians, according to a large 2019 cohort study.

With that said, most people infected with H. pylori never develop stomach cancer.

If you have an H. pylori infection that isn’t causing you any problems and you aren’t at increased risk of stomach cancer, treatment may not offer any benefits.

Stomach cancer, along with duodenal and stomach ulcers, is associated with H. pylori infection. If you have close relatives with stomach cancer or a problem like a stomach or duodenal ulcer, a healthcare professional may recommend treating an H. pylori infection.

Treatment can cure an ulcer, and it may reduce your risk of developing stomach cancer.

Medications

Using medication to treat an H. pylori infection typically involves a combination of antibiotics and a proton-pump inhibitor (a drug that reduces your stomach acid) for up to 14 days. This treatment is sometimes referred to as triple therapy.

Some of the drugs that are used to treat an H. pylori infection include:

Treatment may vary depending on your medical history and if you have allergies to certain medications.

After treatment, you may need a follow-up test for H. pylori. In most cases, only one round of antibiotics is needed to clear the infection. If that doesn’t work, you may need to take other medications.

There’s no vaccine that can protect you from H. pylori, but practicing healthy habits and hygiene can help prevent infection. You can lower your risk of an H. pylori infection by:

  • washing your hands frequently, especially before cooking or eating, or after using the restroom
  • drinking water from a source you know is safe
  • avoiding food that hasn’t been cleaned properly or cooked safely

Most people infected with H. pylori never experience any symptoms or problems related to the bacteria.

If you’re experiencing symptoms and receive treatment, your long-term outlook is generally positive. At least 4 weeks after finishing your treatment, your doctor will test to make sure the medication eradicated the bacteria. You may need to take more than one round of treatment to kill the H. pylori bacteria.

H. pylori infections can lead to peptic ulcers in some people. Treating the H. pylori infection with medication can usually heal a peptic ulcer.

If you develop another condition associated with an H. pylori infection, your outlook will depend on the disease, how soon it’s diagnosed, and how it’s treated. Very few people infected with H. pylori will develop stomach cancer.