H. pylori Infection: The Stomach Germ Half the World Carries, Its Warning Signs, and How Antibiotics Clear It

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026

Source currency note: Clinical content reviewed through December 2023; pages updated December 2025.

TL;DR

Helicobacter pylori (H. pylori) is a common stomach bacterium that may infect more than half of people worldwide at some point in their lives, often during childhood. Most carriers never develop symptoms. When symptoms appear, they usually come from stomach swelling or a peptic ulcer: burning stomach pain, pain that worsens on an empty stomach, bloating, frequent burping, loss of appetite, and weight loss. Treatment almost always combines at least two antibiotics taken at the same time, plus an acid-stopping or ulcer-coating medicine, and follow-up testing confirms the germ is gone at least four weeks after treatment ends.

Quick Answer

• What is an H. pylori infection? An H. pylori infection is a stomach infection caused by the bacterium Helicobacter pylori, which settles into the stomach lining. More than half of people in the world may carry it at some point, usually acquired during childhood. Most people never have symptoms, but the infection can lead to peptic ulcers (about 10% to 15% of carriers) and, much less often, stomach cancer.

• How does H. pylori spread? The germs pass from person to person through contact with saliva, vomit, or stool — including through poor hand hygiene and sharing food or utensils. They can also spread through contaminated surfaces and tainted food or water.

• What are the symptoms? An ache or burning pain in the stomach, pain that feels worse when the stomach is empty, upset stomach, loss of appetite, frequent burping, bloating, and weight loss. Most infections cause no symptoms at all.

• When is it an emergency? Get help right away for sharp, sudden, or very severe stomach pain that does not improve; bloody or black, tarry stools; vomit with blood or a coffee-grounds appearance; trouble swallowing; or unusual tiredness with dizziness or passing out.

• How is it diagnosed? Through a stool antigen or PCR test, a urea breath test (for adults and children over 6), or an upper endoscopy with biopsy when more detail is needed.

• How is it treated? With at least two antibiotics at once — to prevent resistance — plus medicines that help the stomach heal, such as proton pump inhibitors, bismuth subsalicylate, or H-2 blockers. Follow-up testing at least four weeks after treatment confirms the cure.

• How can you prevent it? By not sharing food or utensils, washing hands regularly, and drinking safe, treated water.

What Is an H. pylori Infection?

Helicobacter pylori (H. pylori) is a common stomach infection caused by a bacterium of the same name. The germ is a spiral-shaped bacteria that burrows into the stomach lining, where it can live quietly for years without causing any trouble at all.

That quiet period is the defining feature of this infection. Most people who become infected never develop symptoms. More than half the people in the world may carry H. pylori at some point in their lives, and these infections most often begin during childhood — especially in developing countries, where clean water and safer living conditions can be harder to access.

When the infection does cause problems, they come from the way the germ interacts with the stomach. The bacteria can inflame the stomach lining or, over time, wear through the protective coating that shields the stomach from its own acid. That damage leads to sores called peptic ulcers in the lining of the stomach or small intestine. Much less often, the infection can contribute to stomach cancer.

The bacteria spread through contact with an infected person's bodily fluids — vomit, stool, or saliva. That includes contact through poor hand hygiene, as well as through contaminated surfaces and tainted food or water.

Key Facts at a Glance

Fact	Detail
What it is	A common stomach infection caused by Helicobacter pylori bacteria
How common	More than half of people worldwide may be infected at some point
When it starts	Often during childhood, especially in developing countries
How it spreads	Saliva, vomit, stool; contaminated surfaces; tainted food or water
Symptoms	Most people have none; when present, usually burning stomach pain, bloating, burping
Complications	Peptic ulcers (about 10%–15% of carriers); much less often, stomach cancer
Treatment	At least two antibiotics at once, plus acid-stopping or ulcer-coating medicine
Cure confirmation	Follow-up test at least 4 weeks after finishing treatment

What Do H. pylori Symptoms Feel Like?

Most H. pylori infections don't cause symptoms. When a person does feel something, the symptoms usually come from swelling of the stomach lining or from a peptic ulcer the infection has helped create.

The most common experience is an ache or burning pain in the stomach area, which doctors call the abdomen. The pain often feels worse when the stomach is empty — for example, between meals or in the night — because there is no food in the stomach to buffer the acid.

Beyond pain, the infection can produce a cluster of digestive symptoms that many people mistake for a general upset stomach: bloating, frequent burping, and a feeling of an unsettled stomach. Loss of appetite and weight loss can also develop, particularly when an ulcer is present.

Symptom	What you'd notice
Burning stomach pain	An ache or burn in the upper abdomen
Pain worse on empty stomach	Discomfort that builds between meals or at night
Upset stomach	General queasy, unsettled feeling
Frequent burping	Repeated belching beyond what is normal for you
Bloating	Feeling full, swollen, or gassy in the abdomen
Loss of appetite	Wanting to eat less than usual
Weight loss	Unintended loss of body weight

When Should You See a Doctor?

Make an appointment with your healthcare professional if you have ongoing stomach pain or other stomach symptoms. Persistent digestive trouble deserves an explanation, and H. pylori is a common one.

Some symptoms, however, move past "make an appointment" territory and call for urgent care.

Get medical help right away for sharp, sudden, or very bad stomach pain that doesn't get better (can signal a perforated ulcer or other serious complication); bloody or black, tarry stools (indicates bleeding inside the digestive tract); bloody or black vomit, or vomit that looks like coffee grounds (indicates bleeding in the stomach); trouble swallowing (can signal narrowing or a more serious esophageal problem); or unusual tiredness, dizziness, or passing out (suggests significant blood loss or anemia).

What Causes an H. pylori Infection?

H. pylori infections are caused by H. pylori germs that get into the stomach lining. The germs are passed from person to person through contact with saliva, vomit, or stool. They can also spread through contaminated surfaces, or through tainted food or water.

This explains why the infection often starts in childhood and clusters in households and communities. Once the bacteria settle into the stomach lining, they can remain there for decades unless antibiotic treatment removes them.

Who Is Most at Risk?

Your risk of H. pylori infection comes down to your living conditions, health history, and eating habits.

Risk factor	What it means
Living in crowded conditions	Living in a home with many people raises the chance of person-to-person spread
Lacking reliable clean water	Germs can spread through water that hasn't been treated enough for safety
Living in a developing country	Infections are more common in developing nations, where clean water and living conditions may be harder to access; infections there are more common during childhood
Atrophic gastritis	Ongoing swelling and thinning of the stomach lining raises risk
Pernicious anemia	This immune system condition increases risk
Gastric adenomas	These non-cancerous stomach tumors raise risk
Family history	A parent or sibling with peptic ulcers or stomach cancer raises your risk
Sharing food or utensils	The germs spread through saliva, so shared plates and silverware can carry them

What Complications Can H. pylori Cause?

Left untreated, an H. pylori infection can lead to other health conditions called complications. The three main ones are ulcers, inflammation of the stomach lining, and — much less often — stomach cancer.

Ulcers

H. pylori can damage the protective lining of the stomach and small intestine. That damage lets stomach acid create an open sore called an ulcer. About 10% to 15% of people with H. pylori develop an ulcer.

A peptic ulcer is a sore on the lining of the stomach, small intestine, or esophagus. The specific name depends on location:

Ulcer type	Where it forms
Gastric ulcer	In the stomach
Duodenal ulcer	In the duodenum, the first part of the small intestine
Esophageal ulcer	In the lower part of the esophagus

Gastritis

H. pylori infections can irritate and swell the stomach lining — irritation and swelling that doctors call gastritis. Chronic gastritis can thin the stomach lining over time.

Stomach Cancer

H. pylori infection is a strong risk factor for certain types of stomach cancer. Importantly, only a small number of people with H. pylori infections go on to develop stomach cancer. Limiting salt and pickled foods may help lower the risk of cancer if you have an H. pylori infection.

How Is H. pylori Diagnosed?

Diagnosis involves testing to find out whether your symptoms are actually caused by H. pylori germs. Your healthcare professional may recommend one or more of the following tests.

Stool Tests

A lab checks a sample of your stool for signs of H. pylori germs. The stool antigen test is the common option — it looks for proteins called antigens related to H. pylori infections. A stool PCR test can also find the infection in stool, and it can detect gene changes that may make the germs resistant to the antibiotics used to treat them. The PCR test is more expensive than a stool antigen test and may not be available at all medical centers.

Breath Test

The urea breath test works like this: you swallow a pill, liquid, or pudding that contains tagged carbon molecules in a substance called urea. If H. pylori is present, the germs break down the urea and release carbon. Your body absorbs the carbon and releases it when you breathe out, so you blow into a bag and a device detects the carbon molecules. This test works for adults and for children older than 6 who can follow the test instructions.

Scope Test (Upper Endoscopy)

An upper endoscopy exam checks your upper digestive system. You're given medicine to help you relax, then a camera attached to a long, flexible tube — called an endoscope — is threaded down your throat and esophagus into your stomach and the first part of the intestine (the duodenum). The camera lets your healthcare professional view any issues, and the endoscope can take tissue samples called a biopsy, which a lab checks for H. pylori.

An upper endoscopy is more invasive than a breath or stool test, so it's often not used to diagnose H. pylori alone. It's used for further testing, to look for other digestive conditions, and to figure out exactly which antibiotic will work best — especially if the first antibiotics tried didn't clear the infection.

Test	How it works	Notes
Stool antigen test	Checks stool for H. pylori proteins	The common, first-line option
Stool PCR test	Checks stool for germ DNA	Can find antibiotic-resistant gene changes; more expensive; not available everywhere
Urea breath test	Swallow tagged carbon; blow into a bag	Detects carbon released when germs break down urea; for adults and children over 6
Upper endoscopy	Camera views stomach and duodenum; biopsy checks tissue	More invasive; used when more detail is needed or first treatment failed

The same tests used for diagnosis can confirm that the infection is gone after treatment. As a general rule, you wait at least four weeks after finishing antibiotic treatment to take these follow-up tests.

Some medicines can affect test accuracy, so you may need to pause them — for up to two weeks — before follow-up testing. These include bismuth subsalicylate (Pepto-Bismol) used in ulcer treatment, and acid-reducing medicines called proton pump inhibitors and histamine (H-2) blockers. Your healthcare professional will give you specific instructions about your medicines.

In places where H. pylori infections and their complications are common, healthcare professionals sometimes test healthy people for the infection — a practice called screening. Whether screening helps when you have no symptoms is controversial among experts. If you're concerned about an H. pylori infection, talk with your healthcare professional. For example, screening may be recommended if you have a high risk of stomach cancer.

How Is H. pylori Treated?

Treatment for H. pylori infections usually involves taking at least two different antibiotics at once. Using two antibiotics together helps prevent the germs from resisting the effects of one particular drug. Treatment also typically includes a medicine that helps your stomach heal.

Medicine type	How it works	Examples
Antibiotics	Kill the H. pylori bacteria; always at least two at once	Two or more combined to prevent resistance
Proton pump inhibitors (PPIs)	Stop acid from being made in the stomach	Omeprazole (Prilosec), esomeprazole (Nexium), lansoprazole (Prevacid), pantoprazole (Protonix)
Bismuth subsalicylate	Coats an ulcer and protects it from stomach acid	Sold under names including Pepto-Bismol
Histamine (H-2) blockers	Block histamine, the substance that triggers acid production	Cimetidine (Tagamet HB); used only if PPIs can't be used

Follow-up testing for H. pylori at least four weeks after treatment is recommended. If the tests show the treatment didn't work, you may need more treatment with a different mix of antibiotics.

How to Prevent H. pylori Infection

Prevention is simple and comes down to hygiene. You may be able to help prevent an H. pylori infection by not sharing food or utensils with family or friends.

Because the germs spread through saliva, vomit, stool, and contaminated food and water, regular handwashing and safe drinking water also reduce your risk — particularly for children.

Preparing for Your Appointment

If you have symptoms of an H. pylori infection, see your healthcare professional. Your healthcare team may test and treat you directly, or refer you to a gastroenterologist — a healthcare professional who treats diseases of the digestive system.

At the time you make the appointment, ask if there's anything you need to do in advance — for example, you might be told to restrict your diet before certain tests.

Useful questions to ask include: How did an H. pylori infection cause the complications I'm having? Can an H. pylori infection cause other complications? What kinds of tests do I need? Do I need to do anything to prepare for these tests? What treatments are available? What treatments do you recommend? How will I know if the treatment worked?

Expect your healthcare professional to ask whether your symptoms have been constant or come and go, how serious your symptoms are, when they started, what makes them better or worse, whether family members have had similar symptoms, what medicines or supplements you take regularly, and whether you take pain relievers such as aspirin, ibuprofen, or naproxen sodium.

Conclusion: Don't Let a Silent Infection Become an Ulcer

An H. pylori infection is one of the most common stomach infections on Earth — and one of the most silent. More than half of people worldwide may carry the bacterium, and most never feel a thing. But for the people who do develop symptoms, the infection can grind toward peptic ulcers and, in rare cases, stomach cancer.

The good news is that this infection is highly treatable. A combination of antibiotics plus stomach-healing medicine clears it in most people, and a simple follow-up test confirms the cure. The hard part is knowing to look: persistent burning stomach pain, bloating, and pain that worsens on an empty stomach deserve an explanation.

Your next steps: If you have ongoing stomach symptoms, book an appointment with your healthcare professional this week and ask about H. pylori testing. If you notice any of the five emergency signs — especially bloody or black stools or vomit — seek urgent care immediately. After treatment, take the follow-up test at least four weeks later to confirm the infection is truly gone.

Frequently Asked Questions

Does H. pylori cause symptoms in most people?

No. Most H. pylori infections don't cause symptoms at all. When symptoms do appear, they typically come from swelling of the stomach lining or a peptic ulcer: burning stomach pain, pain that feels worse on an empty stomach, upset stomach, loss of appetite, frequent burping, bloating, and weight loss.

Is H. pylori contagious?

Yes. The germs pass from person to person through contact with saliva, vomit, or stool — including through poor hand hygiene and sharing food or utensils. They can also spread through contaminated surfaces and tainted food or water, which is why infections often begin in childhood within households.

How do you know if you have H. pylori?

Only testing can confirm it. The three main tests are the stool antigen or PCR test, the urea breath test (for adults and children over 6), and an upper endoscopy with biopsy. If you have ongoing stomach pain, ask your healthcare professional about being tested.

Can H. pylori cause stomach cancer?

H. pylori infection is a strong risk factor for certain types of stomach cancer, but only a small number of people with the infection ever develop cancer. Treatment of the infection may lower the chance that an H. pylori ulcer becomes cancerous, and limiting salt and pickled foods may help reduce risk.

What is the treatment for H. pylori?

Treatment usually involves at least two different antibiotics taken at once — to prevent the bacteria from becoming resistant — plus a medicine that helps the stomach heal, such as a proton pump inhibitor, bismuth subsalicylate, or an H-2 blocker. Follow-up testing at least four weeks after treatment confirms the infection is cleared.

How long does it take to get rid of H. pylori?

Treatment runs for the length of your prescribed antibiotic course, typically one to two weeks, plus four or more weeks of waiting before the follow-up test confirms the infection is gone. If the first treatment fails, a different mix of antibiotics is used.

Related guides on Rinnit

H. pylori's most common complication is inflammation of the stomach lining — read more in our guide to gastritis: symptoms, the 8 risk factors, and how to calm an inflamed stomach lining.

References

1. Helicobacter pylori (H. pylori) infection — Symptoms and causes

2. Helicobacter pylori (H. pylori) infection — Diagnosis and treatment

Health information, not medical advice. This article is for general education and is not a substitute for professional diagnosis or treatment. Always consult a qualified healthcare provider about your own health, and seek emergency care for urgent symptoms.