Helicobacter pylori:
eradication that works — not half a course

1. What is Helicobacter pylori?

Helicobacter pylori — H. pylori for short — is a spiral-shaped bacterium that colonises the lining of the stomach and nothing else. That anything can survive there at all is remarkable: stomach acid kills most germs within minutes. H. pylori gets around this by producing the enzyme urease, splitting urea into ammonia and wrapping itself in an alkaline buffer cloud — and that is exactly what the breath test makes use of later. It also drills through the mucus layer with its flagella until it sits close to the lining cells, where conditions are less acidic.^¹

The body responds with permanent inflammation, but usually never gets rid of the bacterium again. What develops from this is a chronic inflammation of the stomach lining that smoulders for decades and remodels the mucosa.^¹,²

In all likelihood you picked the bacterium up as a child, usually within your own family. Catching it for the first time as an adult is considered rare.^¹,²

2. What the bacterium can cause

H. pylori stands at the beginning of a chain of possible stomach conditions. Which of them develops depends on the bacterial strain, on genetics and on the way you live.^¹

• Chronic type B gastritis: the standard consequence — present in practically everyone who carries the bacterium, and usually without symptoms.
• Stomach and duodenal ulcer: the classic connection. For duodenal ulcers H. pylori is the most common cause; once eradication has succeeded, the ulcers usually do not come back.
• MALT lymphoma: a rare lymphatic cancer of the stomach lining that can regress in early stages through eradication alone.
• Atrophic gastritis and stomach cancer: over a long course glandular tissue is lost — and it is through this precursor stage that the raised cancer risk runs. H. pylori is regarded as the most important known risk factor for the most common type of stomach cancer and is classified as carcinogenic by the World Health Organization.^¹,³

What does not belong on this list is heartburn: some people even report more of it after eradication, because acid production picks up again.

3. Symptoms and warning signs

The most important message first: carrying the bacterium usually causes no symptoms at all. People who do have symptoms mostly have them because of a consequence — above all because of an ulcer. What is typical then is burning or gnawing pain in the upper abdomen (with a duodenal ulcer classically on an empty stomach and at night, easing after eating), a feeling of fullness, early satiety, nausea and loss of appetite.^⁴

4. Who should be tested

One principle runs through the whole guideline: test only if a positive result would also lead to treatment. A finding without consequences only creates uncertainty. Typical situations are:^¹

• A stomach or duodenal ulcer — current or in your history. Here eradication is standard.
• Chronic gastritis with symptoms, MALT lymphoma of the stomach, or stomach cancer in a first-degree relative.
• Before planned long-term treatment with NSAIDs or low-dose aspirin if you have had ulcers in the past; special cases such as unexplained iron deficiency anaemia.

And the other side of it: a pure incidental finding with no symptoms and no risk constellation is not automatically an instruction to treat. Eradication is an intensive course of antibiotics with side effects and a resistance risk — benefit and effort are weighed up individually. The decision is made by the treating practice together with you.

5. Diagnosis: breath test, stool test, biopsy

There are two routes to detecting the bacterium: without a gastroscopy (breath test, stool antigen test) and with one (tissue sample). Which is chosen depends on whether a gastroscopy is being done anyway.^¹,³

An antibody test in the blood does not distinguish between a current and a cleared infection and is unsuitable for checking success. Self-tests from the chemist do not replace proper diagnosis.

6. Eradication therapy

“Eradication” means wiping the bacterium out completely. That cannot be done with one antibiotic alone — H. pylori sits protected beneath the mucus layer, and single agents would quickly breed resistance. That is why treatment always combines a high-dose acid blocker with two or three antibiotics, in some regimens with bismuth as well. It is only the less acidic stomach that makes the antibiotics work. Which regimen is chosen depends above all on whether you have had a macrolide in the past (clarithromycin for a respiratory infection, for example). The choice is made by the treating practice.^¹

So do not expect a single tablet: eight to twelve individual doses a day add up quickly.

7. Adherence: this is where success is decided

Eradication is one of the few antibiotic treatments where how reliably you take the tablets also determines what treatment options you will have in future. According to the guideline, taking every dose without a gap counts as a key factor in whether it works — alongside the resistance situation, it is the part that is in your own hands.^¹ The reason lies in the drug levels: if a dose is missed, they drop into a range in which the bacterium is no longer killed but is still being provoked. If it is precisely the toughest bacteria that survive, it is precisely those that go on multiplying — half a course breeds resistance, and at the next attempt there are fewer agents left to use. The mechanism is explained in the article Antibiotic resistance.

• Ask for the dosing schedule in writing — which tablet when, with or without food. Have it written down for you at the practice or the pharmacy.
• Set an alarm for every single dose — not just morning and evening; with bismuth regimens four times a day is usual. A weekly pill organiser makes gaps visible: How to take medications.

And if something does go wrong: a forgotten dose is usually taken as soon as you notice — but never a double dose at once. If the next dose is almost due, it is usually skipped. The ground rules are in Missed a medication and Taking antibiotics correctly.

8. Sitting out the side effects rather than stopping

An eradication course is rarely pleasant — that is the expected consequence of several antibiotics over ten to fourteen days. People who know in advance what is coming are less likely to stop.

• A metallic taste — typical of clarithromycin and metronidazole, and it goes once the course ends.
• Loose stools through to diarrhoea — the antibiotics hit the gut flora as well; drink plenty.
• Nausea and loss of appetite — often better if the tablets are not taken on an empty stomach.
• Dark stool and a dark tongue with bismuth, plus headache and tiredness — usually mild.

For metronidazole the product information advises avoiding alcohol during the course and for a few days afterwards — see Medications and alcohol. Whether probiotics improve tolerability is an open question.

9. Checking success and a second attempt

Eradication only counts as successful once it has been verified — a stomach that is still colonised remains a risk factor.^¹,³ The usual approach is a breath test or stool antigen test no earlier than four weeks after the last antibiotic and after at least two weeks without an acid blocker; before that the result easily comes out falsely negative. If there was an ulcer, a follow-up gastroscopy is often arranged.

If the test stays positive, that is no disaster: for the second attempt a different regimen is chosen and antibiotics already used are avoided. Before a third attempt, resistance testing from a tissue sample is usual.^¹ So take a note of which agents you took and for how long — a well-kept medication list saves a lot of guesswork.

10. Preventing stomach cancer

The connection is well established: H. pylori is regarded as the most important known risk factor for the most common type of stomach cancer and is classified as carcinogenic by the World Health Organization.^¹,³ Two things belong alongside that. The absolute probability stays low — the great majority of those who carry the bacterium never develop stomach cancer. And the benefit is greatest when treatment happens early, before the lining has been remodelled; where changes are already advanced, eradication lowers the risk but does not remove it. This matters particularly if a first-degree relative has had stomach cancer — here the guideline expressly recommends testing and treatment.^¹

11. Everyday life during and after the course

• Time the appointments sensibly — the start of the course, the last day of tablets, the PPI pause and the follow-up test all belong in one calendar.
• Take a critical look at NSAIDs and smoking — ibuprofen and its relatives are hard on the stomach lining, and smoking encourages ulcers; see Stomach problems from medications. And do not simply carry on taking a PPI indefinitely once the course is over.

If symptoms persist afterwards, there is often a functional stomach disorder, reflux or irritable bowel syndrome behind them. That is another reason the follow-up test is worth it: it separates “the bacterium is still there” from “the bacterium has gone, the symptoms have stayed”.

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