Functional dyspepsia is a very common medical condition, which occurs in up to 30% of people in the community. However, results of current pharmacological treatment on functional dyspepsia are unsatisfactory. Rifaximin is a minimally absorbed antibiotic that has been used in treatment of non-constipated irritable bowel syndrome (IBS). In particular, bloating and abdominal pain was improved by rifaximin treatment in this group of IBS patients. Whilst there is considerable overlap in symptoms of functional dyspepsia and IBS, the investigators test whether rifaximin is also effective in curing post-prandial distress symptoms related to dyspepsia.

The aim of this study is to test the effects of rifaximin, a minimally absorbed antibiotics, on symptoms of patients with functional dyspepsia.

Inclusion Criteria:

• Non-ulcer dyspeptic patients who fulfill post-prandial distress syndrome according to the Rome III Criteria
• Active dyspeptic symptom
• Normal upper endoscopy
• Urea Breath Test -ve or Rapid urease test -ve
• Not typical gastroesophageal reflux or biliary colic symptoms, but presence of infrequent acid reflux is allowed

Exclusion Criteria:

• No active dyspeptic symptom
• Allergic to rifaximin
• Recent antibiotics use in the past 8 wk
• Recent PPI or H2RA in past 4 wk
• On anti-coagulants, anti-convulsant or oral contraceptives
• On NSAIDs, aspirin or Clopidogrel
• Pregnancy or breast feeding
• Previous gastric surgery