Cryotherapy of common viral warts at intervals of 1, 2 and 3 weeks.

We studied the efficacy, and time to clearance, of more frequent cryotherapy of viral warts, by randomizing 225 patients to receive treatment at 1-, 2- or 3-weekly intervals. The mean times to clearance of warts in each group were 5.5, 9.5 and 15 weeks in the weekly, 2-weekly and 3-weekly groups, respectively (P < 0.01). Cure rates after 3 months correlated with frequency of treatment (P < 0.05). After 3 months, 43% (66% of non-defaulters) had cleared in the group treated weekly, 37% (47%) of the group treated every 2 weeks, and 26% (30%) of those treated every 3 weeks. The mean numbers of treatments needed to achieve clearance were similar in each group (5.5, 4.75 and 5 treatments). After 12 treatments, cure rates were similar for all three groups: 43% for the weekly-treated group (3 months), 48% for the 2-weekly group (6 months), and 44% for the 3-weekly group (9 months). Percentage cure is related to the number of treatments received, and independent of the interval between treatments. A more rapid cure may, therefore, be achieved by more frequent treatment.