H. pylori can cause inflammation of your stomach’s lining, which is known as gastritis. The infection is also considered the primary cause of peptic ulcers — sores in the lining of your stomach or duodenum (a part of the small intestine). Additionally, H. pylori is a risk factor for some types of stomach cancer. Treating the infection can improve gastritis symptoms, eliminate ulcers, and may reduce your chances of developing stomach cancer, too. (1)

H. Pylori and Gastritis

When H. pylori bacteria irritate your stomach, inflammation can occur. Most cases of gastritis are due to the H. pylori infection, but other causes include drinking too much alcohol, the use of nonsteroidal anti-inflammatory drugs — NSAIDs, such as aspirin (Vazalore) or ibuprofen (Advil) — and other medical conditions.   Gastritis doesn’t always cause symptoms, but you may experience:

A gnawing or burning pain in your upper abdomen (that may worsen or improve after eating)IndigestionNausea VomitingFeeling full after eating a small portion

In some instances, gastritis can lead to ulcers, stomach bleeding, and even stomach cancer. (2)

H. Pylori and Ulcers

Only about 10 percent of people with the H. pylori infection will develop an ulcer. (3) But about 90 percent of duodenal ulcers and up to 80 percent of stomach ulcers are caused by H. pylori. (4)  The infection injures the mucous coating that protects the lining of your stomach and duodenum. Once this coating is damaged, stomach acid can creep through to the sensitive lining. The acid and the bacteria irritate the lining of your stomach and small intestine, causing an ulcer to form. About 1 in 10 people in the United States develop an ulcer at some point in their lives, according to Harvard Medical School. Other causes of ulcers include the use of NSAIDs, and rare tumors in the stomach. Doctors now know that spicy foods and stress do not cause ulcers. Symptoms of an ulcer may include (5):

Abdominal pain or discomfort that’s worse when your stomach is emptyBurning stomach painA feeling of fullness or bloatingFrequent burpingHeartburnNausea Unexplained weight lossVomiting of blood

H. Pylori and Stomach Cancer

In recent years, scientists have found an association between the H. pylori infection and the development of stomach cancer. Specifically, H. pylori is linked to an increased risk of “non-cardia” stomach cancers. These types of cancers affect different areas of the stomach but not the top portion. (6) There’s no evidence that H. pylori increases the risk of “cardia” stomach cancers. In fact, some research has shown the infection may actually lower the risk of cardia cancers, but more studies are needed to confirm this association. In 1994, the International Agency for Research on cancer labeled H. pylori as a carcinogen (something that causes cancer). Since then, doctors have accepted the idea that this infection is an important risk factor for certain types of stomach cancers and a cancer known as gastric mucosa-associated lymphoid tissue (MALT) lymphoma. On the other hand, H. pylori is linked to a lower risk of esophageal cancer, according to a meta-analysis published in 2013. Stomach cancer is the second most common cause of cancer-related deaths in the world (lung cancer is the most common). This type of cancer is less common in the United States and other Western countries but more prevalent in Asia and South America. (6) Other risk factors for stomach cancer include:

Having chronic gastritisBeing a manBeing olderHaving a family history of stomach cancer Eating a lot of salt and smoked foods Having pernicious anemia (a condition that happens when the body can’t absorb enough vitamin B12) SmokingHaving a history of stomach surgeries

Your doctor might recommend that you get tested for the H. pylori infection if you have a strong family history of stomach cancer along with other risk factors. Regular checkups with your physician may help spot cancer earlier. (6)

The Role of Treatment

Treatment for H. pylori infection usually involves a combination of one or more antibiotics along with a proton pump inhibitor (PPI) medicine, which helps reduce acid. Taking these therapies to target the infection can often eliminate symptoms of gastritis. The antibiotics plus PPI regimen can permanently cure about 80 to 90 percent of peptic ulcers. (7) Some research has shown that treatment to eradicate H. pylori may also reduce the risk of stomach cancers. A study from 2012 found the incidence of stomach cancer was reduced by nearly 40 percent during an almost 15-year period after participants received treatment for H. pylori.

The Bottom Line

Most people with H. pylori won’t develop any problems. But the infection can put you at risk for gastritis, ulcers, and stomach cancer. It’s important to see your doctor if you have any stomach issues. A simple round of antibiotics and acid-reducing medicines may be able to cure your symptoms. Talk to your healthcare provider if you think you may have the H. pylori infection.