Synopsis
Choose an accurate Helicobacter pylori test, remove drug-related false-negative conditions, prescribe a complete resistance-aware eradication course, and verify cure when ulcer risk makes failure consequential.
- For active infection or cure, use carbon-13 breath testing or a validated laboratory monoclonal stool-antigen assay. The latter cure indication has modern 2023 consensus support; NICE CG184 retains older breath-test-only cure wording.
- Before breath or stool testing, leave two weeks without a PPI and at least four weeks after antibiotics or bismuth; antibody serology cannot establish eradication.
- Biopsy-based histology, rapid urease testing or culture is useful when endoscopy is already indicated, but sampling site and concurrent acid suppression affect yield.
Key red flags
Dysphagia, recurrent vomiting, haematemesis, melaena, iron-deficiency anaemia or measured weight loss requires investigation for structural disease rather than repeated non-invasive testing alone.
A negative breath or stool test taken during PPI treatment can be falsely reassuring because acid suppression reduces organism density and test sensitivity.
Severe diarrhoea, rash, jaundice, arrhythmia symptoms or anaphylaxis during triple therapy requires urgent drug review.
Reasoning priorities
Detect active urease-producing H pylori before treatment or at test of cure.
Confirm PPI and antibiotic washout; a negative result obtained during suppression may need repeat testing under valid conditions.
Worked reasoning
A 44-year-old with previous duodenal ulcer has persistent dyspepsia; a stool antigen test obtained while taking omeprazole was negative. His regular medicines include simvastatin; renal and hepatic function are normal.
- Confirm that there are no alarm symptoms, stop omeprazole for two weeks and ensure no antibiotic or bismuth exposure occurred in the preceding four weeks.
- A carbon-13 urea breath test after the valid washout is positive, showing that the earlier on-treatment result was falsely negative.
- The allergy and prior-antibiotic history permits the licensed clarithromycin combination, QT and electrolyte checks are satisfactory, and pharmacy arranges suspension of simvastatin during the seven-day course because concomitant use is contraindicated. Give omeprazole 20 mg, amoxicillin 1 g and clarithromycin 500 mg, each orally twice daily for seven days, with a written restart and adherence plan.
- At a correctly timed post-treatment review, repeat breath testing is negative and the patient confirms all 14 twice-daily doses were completed; document eradication and the plan if ulcer symptoms recur.
Key medicines
Omeprazole, amoxicillin and clarithromycin eradication exampleFor a suitable adult, give omeprazole 20 mg orally twice daily, amoxicillin 1,000 mg orally twice daily and clarithromycin 500 mg orally twice daily for 7 days. Select this licensed example only when penicillin and macrolide exposure, allergy, interactions and current local resistance guidance permit it. Take the omeprazole capsule whole with water, using the morning and evening schedule for this twice-daily course; do not chew or crush the capsule or enteric-coated pellets. Swallow amoxicillin 500 mg capsules whole with water without opening them; food does not impair absorption. Clarithromycin film-coated tablets can be taken with or without food.Amoxicillin is contraindicated with any penicillin hypersensitivity or a previous severe immediate reaction to another beta-lactam. For the selected 500 mg capsule, GFR 10–30 mL/min permits at most 500 mg twice daily and GFR below 10 at most 500 mg daily; do not apply this normal-function 1 g twice-daily eradication schedule to those patients. Monitor hepatic disease and review methotrexate or warfarin interactions. Clarithromycin requires half-dose reduction at CrCl below 30 mL/min and is contraindicated in severe hepatic failure with renal impairment, previous QT prolongation or ventricular arrhythmia, and hypokalaemia or hypomagnesaemia. Do not coadminister simvastatin/lovastatin, colchicine, oral midazolam, domperidone, ticagrelor, ranolazine or other contraindicated CYP3A4/QT medicines in its label. Suspend the contraindicated statin during an essential clarithromycin course or select a compatible regimen. Omeprazole is contraindicated with nelfinavir; discourage concomitant clopidogrel. Renal impairment does not require omeprazole reduction, but hepatic impairment may need only 10–20 mg daily: the fixed example needs adjustment before use. Explain diarrhoea, candidiasis and allergy, and stop and assess serious hypersensitivity or severe persistent diarrhoea.
Alternative after clarithromycin failure: omeprazole, amoxicillin and metronidazoleFor a suitable adult with no penicillin allergy or prior metronidazole exposure, give omeprazole 20 mg, amoxicillin 1 g and metronidazole 400 mg, all orally every 12 hours for seven days. This follows NICE second-line antibiotic selection and the NHS Lothian dose example, subject to local resistance advice. The selected metronidazole 400 mg film-coated tablet supplies product safety; this adult H pylori course is guideline-supported off-label use for that product. Swallow it with water without chewing, during or after food. Use the capsule administration and renal/hepatic qualifications in the preceding card for omeprazole and amoxicillin.Do not use metronidazole with nitroimidazole hypersensitivity; the amoxicillin beta-lactam contraindications still apply. Metronidazole itself needs no routine renal dose reduction, although dialysis removes it and requires post-haemodialysis redosing; this does not remove amoxicillin renal restrictions. In hepatic encephalopathy its label reduces total daily metronidazole to one-third, possibly once daily, so do not use this fixed tablet regimen unchanged: arrange a measurable adjusted formulation and specialist eradication plan. Avoid alcohol during the course and for at least 48 hours afterwards; monitor INR and adjust warfarin if needed. Arrange lithium taper/withdrawal with the prescriber before treatment and monitor lithium, creatinine and electrolytes if coadministration is necessary. Stop and review neurological toxicity or severe skin reactions. In Cockayne syndrome use only if no alternative and benefit outweighs risk, with liver tests before, during and after treatment. Review pregnancy, lactation, disulfiram and other interactions before prescribing.