Lack of effect of oral acyclovir on prevention of aphthous stomatitis.

Aphthous stomatitis (canker sores) is a common cause of recurrent mouth ulceration. The effect of long-term oral acyclovir therapy on aphthous stomatitis recurrences was evaluated in 44 patients who were in a double-blind treatment trial for recurrent genital Herpes simplex infections. Twenty-five subjects received oral acyclovir daily for one year, while 19 received the drug only during outbreaks of herpes. The number of patients who experienced recurrences of aphthous stomatitis and the frequency and duration of attacks per patient were not significantly different between groups. Furthermore, no consistent change in attack rate was observed in members of either group compared to that reported before they had entered the trial. We conclude that oral acyclovir is not effective for prevention of recurrent aphthous stomatitis in most patients.