Treatment efficacy
Evidence of efficacy of OTC treatments for warts and, particularly, verrucas is sparse and inconclusive.
The latest Cochrane Systematic Review1, of 85 trials involving a total of 8,815 randomised participants evaluated the efficacy of salicylic acid and cryotherapy (with liquid nitrogen), as well as treatments available only on prescription or not obtainable in the UK, in the treatment of warts. Its conclusions included the following:
- Many studies were judged to be at high risk of bias in one or more areas of trial design
- Trials of salicylic acid versus placebo showed that it significantly increased the chance of clearance of warts at all sites, and subgroup analysis for different sites suggested that it might be more effective for hands than feet
- A meta-analysis of cryotherapy versus placebo for warts at all sites favoured neither intervention nor control
- The evidence remains more consistent for salicylic acid, but it only shows a modest therapeutic effect
- Overall, trials comparing cryotherapy with placebo showed no significant difference in effectiveness, but the same was also true for trials comparing cryotherapy with salicylic acid.
Several trials have been carried out in the efficacy of duct tape. Results of most have been inconclusive, although one found duct tape to be more effective than cryotherapy with liquid nitrogen.2
References
1.    Kwok CS, Gibbs S, Bennett C, Holland R, Abbott R. Topical treatments for cutaneous warts. Cochrane Database Syst Rev. 2012 Sep 12;9:CD001781. doi: 10.1002/14651858.CD001781.pub3.
2.    Focht DR 3rd, Spicer C, Fairchok MP. The efficacy of duct tape vs cryotherapy in the treatment of verruca vulgaris (the common wart). Arch Pediatr Adolesc Med. 2002;156:971-4.