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Helicobacter pylori

Helicobacter pylori is a type of bacteria. It's commonly found in the stomach. Many people with Helicobacter pylori have no symptoms at all, but it can cause stomach irritation (gastritis) and stomach ulcers.

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What is Helicobacter pylori?

Helicobacter pylori (commonly shorted to H. pylori) is a germ (bacterium). It can infect the lining of the stomach and duodenum (the first part of the intestine).

How common is Helicobacter pylori infection?

H. pylori infection is very common. Globally, around half of all people have it. It is more common in developing countries.

In the UK, roughly 3 to 4 out of every 10 people have H. pylori. H. pylori infection seems to be becoming less common over time. Once someone gets H. pylori, unless treated, it usually stays for the rest of their life.

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Helicobacter pylori symptoms

Most people with H. pylori have no symptoms at all.

H. pylori can cause stomach irritation (gastritis), stomach and duodenal (small bowel) ulcers. It can - rarely - cause stomach cancer. (See "Complications of Helicobacter pylori", below.

Common symptoms of H. pylori gastritis or ulcers include:

  • Pain in the top part of the abdomen (stomach), below the ribcage and in the middle.

    • This can feel like an ache, a discomfort, a burning pain, or sometimes a sharp pain.

    • The pain is often affected by eating; it may get worse after eating, although sometimes it improve after eating.

  • Nausea (feeling sick).

  • Frequent burping.

Other symptoms, which can suggest a more serious problem, like a bleeding ulcer or stomach cancer, include:

What causes Helicobacter pylori infection?

We don't fully understand exactly how H. pylori spreads. It's thought to spread from person to person. Most people seem to get it in childhood, probably from their parents or siblings.

We think that people catch H. pylori after it gets into the mouth, and is swallowed into the stomach, where it then lives. Ways in which this might happen include:

  • Contact with saliva from an infected person; for example by kissing, or getting infected saliva on the hands and then touching the mouth.

  • Contact with vomit from an infected person; for example by getting traces of it on the hands and then touching the mouth.

  • Contact with faeces (poo) from an infected person; for example by getting traces of it on the hands and touching the mouth, or by drinking water or eating food that has been contaminated by sewage.

Some developing countries have higher rates of H. pylori. It's thought that this might be due to crowded conditions and sanitation problems, such as unsafe or contaminated drinking water.

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Complications of Helicobacter pylori

Most people who have H. pylori have no symptoms at all, and never develop any problems from it.

It can, though, cause problems for some people. These include:


Gastritis means inflammation of the lining of the stomach. This can cause symptoms such as upper abdominal (tummy) pain and nausea.

This happens when H. pylori damages the lining of the stomach. The body's immune system reacts to this damage by producing inflammation. H. pylori releases chemicals that damage the lining of the stomach. It also releases chemicals that seem to trigger inflammation directly.

Gastritis can occur with or without stomach or duodenal ulcers.

Stomach and duodenal ulcers

An ulcer is a break - like a sore - in the lining of an organ. H. pylori can cause these to happen in the stomach and the duodenum. The duodenum is the first part of the small bowel; it's connected to the stomach, and food passes from the stomach into the duodenum during digestion.

H. pylori is the most common cause of stomach and duodenal ulcers. It causes ulcers in the same way that it causes gastritis, by triggering inflammation and damage of the lining of the stomach or duodenum. The protective barrier that prevents acid damage to the stomach seems to be affected, too. It can also cause the stomach to produce more acid, which causes damage to the duodenum.

Stomach and duodenal ulcers have similar symptoms to gastritis, including upper abdominal (tummy) pain and nausea. Eating often affects the pain; the pain can get better or worse after eating, depending on the type of ulcer - but it's not very consistent.

Stomach and duodenal ulcers can bleed. If this is a slow bleed, it might lead to slow blood loss over time, causing anaemia. A large bleed can cause symptoms such as vomiting up blood and passing black, sticky, tar-like poo (digested blood, or melaena). A heavily-bleeding ulcer is serious and can even be life-threatening.

If stomach and duodenal ulcers become deep enough, they can erode all the way through the wall of the stomach or duodenum, making a hole and 'bursting' the organ. This is called a perforation. A perforated ulcer often requires emergency surgery and can be life-threatening.

In the UK, though, perforated ulcers have become much less common over time. This is probably because stomach ulcers are picked up and treated long before they get to this stage.

Stomach cancer

H. pylori increases the risk of developing stomach cancer. However, the vast majority of people with H. pylori do not get stomach cancer. The increased risk from H. pylori infection is small.

The risk of stomach cancer may be greater for people who have H. pylori as well as having a first-degree relative (mother, father, brother, sister or child) who has been diagnosed with stomach cancer.

H. pylori is also closely linked to a rare and unusual type of stomach cancer, called mucosa-associated lymphoid tissue lymphoma (MALT lymphoma), a type of non-Hodgkin's lymphoma.

H. pylori is thought to cause cancer by causing chronic (long-lasting) inflammation of the lining of the stomach, which can cause stomach cells to develop into cancer cells.

H. pylori infection may actually reduce the risk of developing oesophageal (food pipe or gullet) cancer. It's thought that H. pylori might reduce the amount of stomach acid entering the oesophagus (reflux), reducing the risk of damage to the oesophagus.

Who should be tested for Helicobacter pylori and treated if it is found?

Common reasons to test

Frequent reasons to test for H. pylori include:

  • If someone has symptoms of dyspepsia ('indigestion').

    • In the UK, national guidelines say that doctors and patients can either test for H. pylori straight away, or try other treatments first for a month (lifestyle changes and acid-lowering medicines), and test for H. pylori only if those treatments don't work.

    • This is because we don't really have evidence that shows which of these strategies is better. H. pylori is becoming less common in the UK and is relatively rare in some parts of the country.

    • So, if H. pylori is unlikely, it might be reasonable to try other treatments first, and only test if they don't work.

    • If H. pylori is more likely (eg in people of North African descent, where H. pylori is more common), then it might be better to test and treat straight away.

  • If someone has a stomach ulcer or duodenal ulcer.

  • If someone has gastritis.

  • Before starting a non-steroidal anti-inflammatory drug (NSAID), if someone has previously had a stomach or duodenal ulcer.

Other reasons to test

Sometimes, people might have H. pylori testing for another reason - although these are less common. These include:

  • If someone has an unexplained iron-deficiency anaemia, and the cause is still unknown after having a stomach endoscopy, a colonoscopy, and tests for other causes.

  • If someone has a first-degree relative (parent, child, or sibling) with stomach cancer, as testing and treating H. pylori may reduce their risk of developing stomach cancer.

  • If someone has a MALToma.

  • If someone has a condition called chronic idiopathic thrombocytopenic purpura. There is some evidence that H. pylori is linked to this condition, and that treating H. pylori helps.

Screening for H. pylori

At the moment, we don't test for H. pylori unless people have symptoms, or another specific reason to test. Testing healthy people without symptoms is called 'screening'.

H. pylori screening isn't recommended, at least in the UK. This is because there is thought to be little benefit. For people who have no symptoms, treating H. pylori can't make them feel any better - because they already don't have any symptoms.

Detecting and treating H. pylori might reduce the risk of stomach cancer; however, in the UK, stomach cancer is relatively uncommon, and H. pylori is also becoming less common over time. So, a very large number of people would need to be tested and treated to prevent one person developing stomach cancer; it's possible that more people would be harmed through antibiotic side effects than are helped.

Some researchers have suggested that H. pylori screening might be effective in other countries where both H. pylori and stomach cancer are much more common, though, such as some East Asian countries.

How is Helicobacter pylori diagnosed?

Various tests can detect H. pylori:

  • A urea breath test can confirm a current H. pylori infection.

    • In this test, you drink a special liquid that contains a chemical called urea.

    • You then give a breath sample. This is then analysed in a lab.

    • H. pylori breaks down urea. So, if H. pylori is present, breakdown products of urea will be found in the breath sample.

    • Note: prior to this test you should not have taken any antibiotics for at least four weeks. Also, you should not have taken a proton pump inhibitor (PPI) or H2-receptor antagonist medicine for at least two weeks. (These are acid-lowering medicines.) Also, you should not eat anything for several hours before the test (check the exact test for instructions). Medication and food can affect the test result.

  • An alternative test is the stool antigen test.

    • In this test, a pea-sized sample of poo (faeces) is tested for traces of H. pylori.

    • Note: prior to this test you should not have taken any antibiotics for at least four weeks. Also, you should not have taken a PPI or H2-receptor antagonist acid-suppressing medicine for at least two weeks. These can affect the result.

  • A blood test can detect antibodies to H. pylori.

    • This can show if someone has been infected with H. pylori. However, the blood test can't tell between a current infection, and a previous infection that has resolved or been successfully treated.

    • Therefore, it can't be used to check if an infection has cleared following treatment.

    • It also has a high 'false positive' rate - being positive in some people who no longer have H. pylori - so is used less often now in the UK.

If needed, the breath test or stool antigen test is usually used to check if an infection has cleared following treatment.

Helicobacter pylori treatment


H. pylori is killed by certain antibiotics. However, a combination of medicines is needed to get rid of it completely. This is referred to as triple therapy, although because it gets rid of (eradicates) H. pylori, it is also called eradication therapy.

H. pylori treatment consists of three different medications, taken together for one week. These are two different antibiotics, and an acid-lowering medication. It is important to take all the medication exactly as directed and to take the full course.

Eradication therapy

Eradication therapy clears H. pylori in up to 9 in 10 cases if it is taken correctly for the full course. If you do not take the full course then the chance of clearing the infection is reduced. A second course of eradication therapy, using different antibiotics, will usually work if the first course does not clear the infection.

Eradication therapy is sometimes called triple therapy as it involves three medicines - two antibiotics and an acid-suppressing medicine.

Side-effects of eradication therapy

Up to 3 in 10 people develop some side-effects when they take eradication therapy. These include:

However, it is worth persevering with the full course if side-effects are not too bad. A switch to a different set of medicines may be advised if the first combination does not clear the H. pylori, or if it caused bad side-effects and you had to stop taking it.


If you have indigestion (dyspepsia), it is usually only necessary to check to see if the H. pylori has gone if your symptoms come back after treatment. If you have a gastric or duodenal ulcer, testing is usually done 6-8 weeks after treatment; sometimes, a repeat endoscopy is recommended to check that the ulcer has healed.

How to prevent Helicobacter pylori infection

We don't know exactly how H. pylori spreads, so we don't know a good way to prevent it entirely.

However, given the theories on how it spreads, general hygiene measures may help:

  • Washing hands thoroughly before eating, before preparing food, and after using the toilet.

  • Eating food and drink that has been hygienically prepared.

  • Drinking water from safe, clean sources only.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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