What H. pylori is and how it's caught
Helicobacter pylori (H. pylori) is a spiral-shaped bacterium that lives in the lining of the stomach. It's thought to be one of the most common chronic bacterial infections worldwide, and a large proportion of UK adults carry it at some point in their lives, often without ever knowing. It's usually acquired in early childhood, most likely through close contact within a household or, less often, through contaminated food or water, although the exact route isn't fully understood.
Once established, H. pylori can persist for decades if left untreated. It survives the stomach's acidic environment by burrowing into the protective mucus layer and altering the acid balance around it, which over time can damage the stomach lining. Most people who carry it never develop symptoms at all, but in a minority it leads to chronic inflammation (gastritis), peptic ulcers, or, rarely, stomach cancer after many years.
It isn't caused by stress, spicy food or a particular diet, though those factors can make existing symptoms feel worse. It also isn't typically caught from pets, and once someone has been successfully treated, true reinfection is uncommon in the UK.
Symptoms of H. pylori infection
Most people with H. pylori have no symptoms whatsoever, and the infection is often only discovered incidentally or when someone is investigated for unrelated indigestion. When symptoms do occur, they tend to reflect the gastritis or ulcer it has caused rather than the bacterium itself, and typically include:
- Burning or gnawing pain in the upper abdomen, often worse on an empty stomach or at night
- Bloating, excessive burping, or a feeling of fullness after small meals
- Nausea, and occasionally vomiting
- Loss of appetite or unintentional weight loss
- Heartburn or acid reflux that doesn't fully settle with over-the-counter treatment
These symptoms overlap a great deal with other common digestive conditions, including ordinary indigestion, acid reflux and IBS, so a symptom pattern alone can't confirm H. pylori. Testing is the only reliable way to know whether it's present.
Getting tested: breath test, stool test and endoscopy
In UK primary care, the two most common tests are a urea breath test and a stool antigen test. For the breath test, you swallow a small amount of labelled urea; if H. pylori is present, its enzymes break the urea down in a way that changes the carbon dioxide you breathe out, which the test detects. The stool antigen test checks a small sample for proteins specific to the bacterium. Both are non-invasive, accurate, and widely used to diagnose and later confirm eradication of the infection.
Accuracy depends on preparation: proton pump inhibitors (PPIs) need to be stopped for about 2 weeks and antibiotics or bismuth-containing medicines for about 4 weeks before either test, since both can temporarily suppress the bacterium enough to produce a false negative result. Your clinician will advise exactly when to pause any current medication and for how long.
A blood test that looks for H. pylori antibodies exists but is generally avoided for diagnosis in UK practice, because it can stay positive for a long time after a past infection has already been successfully treated, making it unreliable for confirming a current, active infection. Endoscopy, where a thin camera examines the stomach lining directly and can take a small biopsy, is reserved for people with red-flag symptoms, those over a certain age with new symptoms, or when a clinician needs to rule out other causes rather than as a routine first test for suspected H. pylori.
How H. pylori is treated
First-line NHS treatment is a 7-day course of "triple therapy": a proton pump inhibitor, usually lansoprazole or omeprazole, taken alongside two antibiotics, most commonly amoxicillin and clarithromycin. The PPI reduces stomach acid, which both eases symptoms and creates conditions where the antibiotics work more effectively against the bacterium.
For people with a penicillin allergy, an alternative course swaps out amoxicillin for a combination of clarithromycin and metronidazole, still alongside a PPI. If a first course doesn't successfully clear the infection, often due to antibiotic resistance, a second-line regimen using a different combination of antibiotics is used rather than simply repeating the same one.
Side effects during treatment are usually mild and settle once the course finishes: a metallic taste, mild nausea, loose stools or a temporary change in how food tastes are the most commonly reported. Taking the tablets with food, as directed, and completing the full 7 days, even if symptoms improve early, gives the best chance of eradicating the infection in one course.
Confirming the infection has cleared
A repeat urea breath test or stool antigen test, done at least 4 weeks after finishing antibiotics and with the same PPI washout period observed beforehand, is the recommended way to confirm eradication. This matters particularly if you had a confirmed ulcer, if your symptoms haven't fully settled, or if you're in a group at higher risk of complications.
It's worth repeating that a blood antibody test is not suitable for this follow-up step: antibodies can remain detectable for months or years after the bacterium itself has gone, so a positive antibody result after treatment doesn't necessarily mean the infection is still there.
If the follow-up breath or stool test still shows the infection is present, this usually reflects antibiotic resistance or incomplete treatment rather than a brand new infection, and your clinician will discuss a different antibiotic combination for a second course.
When to see a doctor urgently
Most H. pylori-related symptoms are manageable and not an emergency, but certain symptoms need same-day medical assessment because they can signal a bleeding or perforated ulcer or another serious condition:
- Vomiting blood, or vomit that looks like coffee grounds
- Black, tarry or very dark stools
- Sudden, severe abdominal pain
- Unexplained weight loss alongside stomach symptoms
- Difficulty or pain swallowing
- Persistent vomiting that won't settle
Any of these warrant urgent same-day review rather than waiting for a routine appointment or a breath test slot. Outside of these red flags, if indigestion-type symptoms persist for more than a couple of weeks despite simple measures, it's reasonable to speak to a clinician about whether H. pylori testing is appropriate for you.