(HealthDay News) – Low-dose prophylaxis with penicillin is more effective than placebo in preventing recurrent cellulitis of the leg, but protection disappears after stopping treatment, according to a study published in the May 2 issue of the New England Journal of Medicine.

Kim S. Thomas, PhD, from the University of Nottingham in the United Kingdom, and colleagues randomly assigned 274 patients with ≥2 episodes of cellulitis of the leg to receive placebo or 250mg penicillin twice a day as a prophylactic for 12 months. Participants were followed for a three-year period.

The researchers found that during the prophylaxis phase there were significantly fewer recurrences in the penicillin group (22% vs. 37%; hazard ratio, 0.55; number needed to treat to prevent one recurrent cellulitis episode, five). However, during the no treatment follow-up, the rate of a first recurrence was 27% for both groups. Overall, there were significantly fewer repeat episodes in the penicillin group (119 vs. 164; P=0.02 for trend). The two groups had similar numbers of participants who experienced adverse events (P=0.50).

“In patients with recurrent cellulitis of the leg, penicillin was effective in preventing subsequent attacks during prophylaxis, but the protective effect diminished progressively once drug therapy was stopped,” Thomas and colleagues conclude.

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