OBJECTIVES: NICE recommends the use of proton pump inhibitors (PPIs) at the lowest effective dose in patients with gastroesophageal reflux disease. Changing patients from a standard or high dose PPI to esomeprazole 20mg has shown that only 5% (8/146) of patients returned to a higher dose PPI in the subsequent 6 months. The purpose of this study was to assess the frequency with which patients who had reduced PPI dose to lansoprazole 15mg returned to a higher dose PPI. METHODS: A retrospective audit of electronic patient records at 4 UK general practices identified patients on continuous PPI therapy at standard or high dose who had been switched to lansoprazole 15mg and recorded any changes in PPI therapy during the subsequent 6 months. RESULTS: The audit identified 175 patients previously on regular (>2 PPI prescriptions in the previous 6 months) standard or high dose PPI who had been changed to lansoprazole 15mg. Within 6 months of the first lansoprazole 15mg prescription, 26% (46/175) of patients had changed back to a higher dose PPI. Similar switch rates were obtained if the analysis was restricted to patients who had received > 4 prescriptions in the 6 months prior to their first lansoprazole 15mg prescription (25%: 31/122). Amongst those patients with a specific diagnosis of GORD/RO, 37% (15/41) switched to a higher dose PPI within 6 months. Around half (52%; 16/31) of patients who returned to a higher dose had no specific reason recorded (16/31). However the most commonly recorded reason for failing on lansoprazole 15mg was inadequate control of symptoms (35%; 11/31). CONCLUSION: The proportion of patients changed from standard or high dose PPI to lansoprazole 15mg who required an increase in PPI therapy within 6 months was higher than that reported for patients treated with esomeprazole 20mg.