H. pylori infection occurs when a bacterium called Helicobacter pylori (H. pylori) infects your stomach or the first part of your small intestine.

H. pylori infection is thought to be present in about half the people in the world. For many people, H. pylori infection causes no signs or symptoms and doesn't lead to any complications. But for others, H. pylori can lead to serious complications, such as ulcers and stomach cancer.

In the United States, H. pylori infection rates are declining. In turn, the rates of serious complications are also declining.

Most cases of H. pylori infection produce no signs or symptoms. Signs or symptoms that can occur with H. pylori infection include:

• An ache or burning pain in your abdomen
• Nausea
• Vomiting
• Frequent burping
• Bloating
• Weight loss

When to see a doctor
Make an appointment with your doctor if you notice any persistent signs and symptoms that worry you.

Seek immediate medical help if you experience:

• Severe or persistent abdominal pain
• Difficulty swallowing
• Bloody or black tarry stools
• Bloody or black vomit or vomit that looks like coffee grounds

H. pylori infection is caused by the H. pylori bacterium. H. pylori is primarily passed from person to person through direct contact with saliva or fecal matter. H. pylori can also be spread through untreated water.

H. pylori bacteria enter your body through your mouth and passes into your digestive system. The stomach and its stomach acid make a hostile environment for many bacteria. But the H. pylori bacterium is especially well-adapted for survival in the stomach. It produces an enzyme that, through a series of biochemical processes, creates a low-acid buffer zone for itself.

Many people contract H. pylori as children. Contracting H. pylori in adulthood is much less common. Risk factors for H. pylori infection are related to living conditions in your childhood, such as:

• Living in crowded conditions. You have a greater risk of H. pylori infection if you live in a home with many other people.
• Living without a reliable supply of hot water. Having a reliable hot water supply can help you keep your living area clean and reduce your risk of H. pylori.
• Living in a developing country. People living in developing countries, where crowded and unsanitary living conditions may be more common, have a higher risk of H. pylori infection.
• Living with someone who has an H. pylori infection. If someone you live with has H. pylori, you're more likely to also have H. pylori.

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Ulcers

Many people with H. pylori infection will never have any signs or symptoms and will never develop complications. Others will develop serious complications. It's not clear why this is.

Complications associated with H. pylori infection include:

• Open sores (ulcers) in your stomach and small intestine. H. pylori infection causes the majority of these ulcers.
• Inflammation of the stomach lining. H. pylori infection can irritate the lining of the stomach, causing inflammation (gastritis).
• Stomach cancer. H. pylori infection is a strong risk factor for certain types of stomach cancer, including adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma.

You're likely to start by first seeing your family doctor or a general practitioner if you have signs or symptoms that indicate a complication of H. pylori infection. Your doctor may refer you to a specialist who treats diseases of the digestive system (gastroenterologist).

Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Write down key personal information, including any major stresses or recent life changes.
• Make a list of all medications, as well as any vitamins or supplements, that you're taking.
• Take a family member or friend along, if possible. Sometimes it can be difficult to absorb all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For H. pylori infection, some basic questions to ask your doctor include:

• How did H. pylori infection cause the complications I'm experiencing?
• Can H. pylori cause other complications?
• What kinds of tests do I need?
• What treatments do you suggest for H. pylori infection?
• Will H. pylori treatments relieve my signs and symptoms?
• Should I see a specialist? What will that cost, and will my insurance cover it?
• Is there a generic alternative to the medicine you're prescribing me?
• Are there any brochures or other printed material that I can take with me? What Web sites do you recommend?
• What will determine whether I should plan for a follow-up visit?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may allow more time to cover other points you want to address. Your doctor may ask:

• When did you first begin experiencing symptoms?
• Have your symptoms been continuous or occasional?
• How severe are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?

Tests and procedures used to determine whether you have an H. pylori infection include:

• Blood test. Analysis of a blood sample may reveal signs of an H. pylori infection in your body. A blood sample is usually collected by pricking your finger.
• Breath test. During a breath test, you drink a solution that contains radioactive carbon molecules. If you have an H. pylori infection, the radioactive carbon is released when the solution is broken down in your stomach. Your body absorbs the radioactive carbon and expels it when you exhale. You exhale into a bag and your doctor uses a special device to detect the radioactive carbon.
• Stool test. A laboratory test called a stool antigen test looks for foreign proteins (antigens) associated with H. pylori infection in your stool.
• Using a flexible scope to see inside your stomach. During an endoscopy exam, your doctor threads a long flexible tube equipped with a tiny camera (endoscope) down your throat and esophagus and into your stomach and duodenum. Using this instrument, your doctor can view any irregularities in your upper digestive tract and remove tissue samples (biopsy). These samples are analyzed for H. pylori infection.

Treatment for H. pylori infection typically involves a combination of medications to eradicate H. pylori from your body.

Medications to eliminate H. pylori from your body
Antibiotic medications are used to treat H. pylori infection. Doctors typically prescribe a combination of medications, with the hope that this strategy will help keep H. pylori from developing a resistance to one particular medication. You'll likely take two antibiotic medications for 14 days.

Medications to reduce acid in your stomach
Medications that reduce acid in your stomach may help enhance the effectiveness of antibiotics. Acid-reducing medications may also help alleviate symptoms and promote healing. These medications include:

• Proton pump inhibitors. These prescription medications suppress acids by shutting down "pumps" in acid-producing cells. Examples include omeprazole (Prilosec), lansoprazole (Prevacid), pantoprazole (Protonix), rabeprazole (Aciphex) and esomeprazole (Nexium).
• Histamine (H-2) blockers. These medications reduce the amount of acid released into your digestive tract. H-2 blockers include ranitidine (Zantac), famotidine (Pepcid), cimetidine (Tagamet) and nizatidine (Axid).

Testing for H. pylori after treatment
Your doctor may recommend that you undergo testing for H. pylori several weeks after your treatment. A follow-up breath or stool test may confirm that the H. pylori bacterium is no longer present in your body and treatment was successful.

Or follow-up testing may show that treatment was unsuccessful. In that case, you may undergo treatment again, receiving a different combination of antibiotic medications.

Doctors aren't certain how the H. pylori bacterium is spread, so there's no proven way to prevent H. pylori infection.

Preventing H. pylori complications
In areas of the world where H. pylori infection and its complications, such as stomach cancer, are common, doctors sometimes test healthy people for H. pylori. For instance, stomach cancer is much more common in Asian countries than in the United States. Some doctors argue that treating high-risk people for H. pylori before it causes complications may help prevent serious diseases, such as stomach cancer.

Whether there is a benefit to treating H. pylori when you have no signs or symptoms of infection is controversial among doctors.

If you're concerned about H. pylori infection or think you may have a high risk of stomach cancer, talk to your doctor. Together you can decide whether you may benefit from H. pylori screening.