Ranitidine bismuth citrate (Pylorid, Tritec) is a novel drug which heals peptic ulcers and when co-prescribed with either clarithromycin or amoxycillin eradicatesHelicobacter pylori. In controlled clinical studies it was well-tolerated when given alone or when co-prescribed with either antibiotic. Data from 20 clinical studies are reported in this analysis of safety with almost 5000 patients having received ranitidine bismuth citrate (200, 400, or 800 mg twice daily). The incidence of adverse events reported with this new drug, either alone or with an antibiotic, was not different from or lower than in patients given placebo and was independent of the dose of ranitidine bismuth citrate tested. Most commonly reported events (>1% of patients) were upper respiratory tract infection, constipation, diarrhoea, nausea and vomiting, dizziness, and headache, the latter being the only event reported by >2% of patients who received ranitidine bismuth citrate alone. Adverse events considered by the clinical investigator to be adverse reactions occurred with a similar frequency amongst patients given ranitidine bismuth citrate (8%), ranitidine hydrochloride (6%), or placebo (6%). The incidence of adverse reactions was greater when co-prescribed with amoxycillin (11%) or clarithromycin (20%) although it was not different from that noted with the antibiotics alone. Serious adverse events were reported in similar proportions of patients given placebo, ranitidine bismuth citrate alone or with an antibiotic, and ranitidine hydrochloride (range: <1-2%). The safety profile of ranitidine bismuth citrate was thus comparable to that of ranitidine hydrochloride (Zantac), a drug with a well-established record of safety in clinical use.