Helicobacter Pylori Infection: Testing and Treatment

Testing for H. pylori

Preparing for a breath or stool test

To avoid false-negative results:

• stop proton pump inhibitors (such as omeprazole) for 2 weeks before testing, if your doctor agrees; H2 blockers or antacids can be used instead
• stop antibiotics and bismuth (Pepto-Bismol) for 4 weeks before testing

Treatment regimens

Treatment always combines acid suppression with two or more antibiotics, because single antibiotics fail. Choice depends on local resistance, previous antibiotic use (especially clarithromycin or metronidazole), allergies and any susceptibility testing.

Your doctor will prescribe exact doses. Do not substitute or skip components.

Tips for success

• Take every dose for the full 14 days, even if you feel better. Missing doses is a major cause of failure.
• Set phone reminders; some regimens involve many pills several times a day.
• Take PPIs 30 to 60 minutes before meals.
• Avoid alcohol during and for 3 days after metronidazole, which can cause a severe reaction.
• Tell your doctor about other medicines; clarithromycin interacts with many drugs, including some statins and blood thinners.

Common side effects

• metallic or bitter taste (metronidazole, clarithromycin)
• nausea, stomach upset and diarrhea (antibiotic-associated diarrhea)
• dark or black stools and a dark tongue from bismuth (harmless; different from the sticky black stools of bleeding)
• yeast infections
• sensitivity to sunlight (tetracycline)

Probiotics may reduce side effects such as diarrhea in some people, but they do not replace antibiotics.

Confirming the cure

A test of cure is recommended for everyone treated:

• at least 4 weeks after finishing antibiotics
• at least 2 weeks after stopping PPIs
• using a urea breath test, stool antigen test or biopsy (not a blood test)

If treatment fails

If the follow-up test is still positive:

1. A different regimen is chosen, avoiding antibiotics already used where possible (particularly clarithromycin and levofloxacin).
2. Bismuth quadruple therapy or rifabutin-based therapy are common second-line options.
3. Endoscopy with culture or molecular resistance testing may guide treatment after two failures.
4. Penicillin allergy testing can open up amoxicillin-based options for people with a reported allergy.

After successful treatment

• Peptic ulcers heal and recurrence becomes much less likely.
• Stomach cancer risk falls, particularly when treated before precancerous changes.
• Reinfection is uncommon in adults in the US, though more common in regions with high prevalence.
• Some people still have indigestion after cure, which may be functional dyspepsia.

For background on how H. pylori spreads, its symptoms and complications, see H. pylori infection overview.

Frequently asked questions

What is the best test for H. pylori?

The urea breath test and stool antigen test are the best non-invasive tests for active infection. During an endoscopy, biopsies can be tested. Blood antibody tests are not recommended, because they can stay positive long after the infection is gone.

What is the treatment for H. pylori?

Treatment combines an acid-reducing medicine with two or more antibiotics, usually for 14 days. In the US, bismuth quadruple therapy (PPI, bismuth, tetracycline and metronidazole) is a preferred first choice. Vonoprazan with amoxicillin is an alternative.

How long after H. pylori treatment should I retest?

Retest at least 4 weeks after finishing antibiotics and at least 2 weeks after stopping proton pump inhibitors. Use a breath test, stool antigen test or biopsy. Testing too early can give a falsely negative result.

What if H. pylori treatment does not work?

Your doctor will choose a different antibiotic combination, avoiding the ones already used. Common second-line options include bismuth quadruple therapy or rifabutin-based therapy. After repeated failures, an endoscopy with antibiotic resistance testing helps choose treatment.

Can I drink alcohol while being treated for H. pylori?

Avoid alcohol during treatment and for at least 3 days after finishing if your regimen contains metronidazole, because the combination can cause severe nausea, vomiting, flushing and palpitations. Alcohol can also irritate the stomach lining while it heals.

Why does bismuth turn my stool black?

Bismuth reacts with sulfur in the gut to form a black compound, making stools and sometimes the tongue dark. This is harmless. Sticky, tarry, foul-smelling black stools with dizziness, however, may mean bleeding and need urgent care.