Dual therapy containing high dose of proton pump inhibitor (PPI) and amoxicillin had showed excellent eradication results with Helicobacter pylori first-line treatment. However, no study has examined the the efficacy of high dose of dual therapy or dual therapy plus metronidazole for H. pylori rescue treatment.This study is designed to evaluate the efficacy and safety of the addition of metronidazole to high dose of dual therapy for H. pylori rescue treatment.

Inclusion Criteria:

• Participants with non-ulcer functional dyspepsia or peptic ulcer disease
• Ability and willingness to participate in the study and to sign and give informed consent
• Confirmed H. pylori infection and with previous treatment failure

Exclusion Criteria:

• Less than 18 years old or older than 80 years
• With previous gastric surgery
• Major systemic diseases
• Pregnancy or lactation
• Allergy to any of the study drugs
• Administration of antibiotics, bismuth,antisecretory drugs in 8 weeks prior to inclusion