Background: Recurrent aphthous stomatitis (RAS) is a common disease with unknown etiology. There is no curative treatment. Purslane is considered as a rich source of antioxidants with anti-inflammatory effects. The purpose of this study is to evaluate the effect of Purslane in the treatment of RAS.
Methods: A total of 50 patients were selected for this randomized triple-blind placebo-controlled clinical trial from School of Dentistry of Tehran University of Medical Sciences in 2011. All subjects were randomly divided into two groups. Groups A and B received placebo and Purslane, respectively, for three months. Pain intensity based on the visual analogue scale (VAS), the mean intervals of lesions occurrence, number of lesions and the mean duration of complete healing at baseline and at months 1, 2 and 3 were recorded. 
Results: While no patient complained from increased severity of pain, decreased severity of pain for 4, 3, 2, and 1 grades were recorded in %16, %20, 20%, and 40%, respectively, which were much higher than 4%, 8%, 8%, and 28%, respectively, in the control group. A significant decrease in pain intensity in VAS scores were seen after treatment in group B (P<0.001). The mean duration of complete healing showed significant differences (P<0.001) between groups A (-1.52±4.07 days) and group B (-6.56±4.50 days). The mean intervals between lesions also showed significant differences (P<0.001) between group A (17.88 days) and group B (33.12 days). No significant differences were found between group A and group B regarding to number of lesions. No serious side-effects occurred in either group.
Conclusion: According to our study, Purslane is clinically effective in treatment of RAS and considering the lack of side-effects during the study period, this medicine may be a favorable alternative treatment for recurrent aphthous stomatitis.