• Reduction in the median pain score
  
• Reduction in the median ulcer size
  
• Reduction in the median ulcer number
  
• Reduction in the total number of episodes of ulceration (RAS)
  

• Change in global ulcer severity score
  
• Increase in the proportion of ulcer free days
  
• Difference in the proportion of ulcer free days (comparing trial v baseline)
  
• Side effect incidence
  
• Side effect type
  

There are few effective treatments for recurrent aphthous stomatitis (cancer sores, recurrent mouth ulcers). Most existing treatments are palliative topical treatments. Some systemic drugs e.g. steroids and thalidomide can suppress the recurrence of mouth ulcers but have serious long term side effects. Pentoxifylline (also known as oxpentifylline) has been used systemically for many years to treat peripheral vascular disease and has a good side effect profile. It shares several actions with thalidomide but does not share its serious side effects. Furthermore, some small scale, open label clinical studies have indicated it may be very effective in treating recurrent aphthous stomatitis (RAS). This study enrolled patients with RAS for which no underlying cause could be identified. Patients kept a diary of the pattern of their mouth ulcers for 60 days to confirm the pattern of ulceration and provide baseline data. Those still qualified for the study were then randomized to treatment with pentoxifylline 400mg three times daily or an identical placebo tablet three times daily for a further 60 days during which they continued to keep a daily ulcer diary. At the end of this period, treatment was stopped and they kept the daily ulcer diary for a further 60 days to identify if any benefit from the treatment was continued after ceasing treatment.