Monochloroacetic Acid Application Is an Effective Alternative to Cryotherapy for Common and Plantar Warts in Primary Care: A Randomized Controlled Trial

Cryotherapy and salicylic acid (SA) often fail as treatments for skin warts. We examined the effectiveness of monochloroacetic acid (MCA) for patients with common or plantar warts. Consecutive patients aged 4 years and older with one or more newly diagnosed common or plantar warts were recruited in 53 Dutch general practices. We randomly allocated eligible patients to 13-week treatment protocols of office-applied MCA versus liquid nitrogen cryotherapy every 2 weeks for patients with common warts (n = 188), and MCA versus cryotherapy combined with daily SA self-application for patients with plantar warts (n = 227). The primary outcome was the proportion of patients whose warts were all cured at 13 weeks. In the common wart group, cure rates were 40/92 (43%, 95% confidence interval 34-54) for MCA and 50/93 (54%, 44-64) for cryotherapy (risk difference (RD) -10%, -25-4.0, P=0.16). In the plantar wart group, cure rates were 49/106 (46%, 37-56) for MCA and 45/115 (39%, 31-48) for cryotherapy combined with SA (RD 7.1, 5.9-20, P=0.29). For common warts, MCA is an effective alternative to cryotherapy to avoid pain during the treatment, although pain after the treatment is similar. For plantar warts, office-applied MCA may be preferred over cryotherapy combined with SA, on the basis of comparable effectiveness, less treatment pain, and less treatment burden.