Most treatments for warts poorly untested
MedWire News: The scientific evidence for treating skin warts is flawed and inadequate, according to the authors of a study.
They recommend that salicyclic acid should be considered the "mainstay" for treating warts and propose avoiding other treatments until better evidence is available.
Cutaneous warts are common skin lesions that most often affect the hands and feet. The majority of warts disappear without treatment and they do not cause any ill effects. However, some people ask for treatment because of the social stigma associated with the lesions.
The most common treatment for warts is salicyclic acid, which is generally applied as a cream or gel directly to the affected areas of skin. But there are many other treatments, and little is known about their safety or effectiveness.
To investigate, Drs Thierry Simonart and Viviane De Maertelaer, both from Université Libre de Bruxelles, Belgium, searched the scientific literature and specialist textbooks, looking for studies that tested different treatments for warts.
Despite their extensive search, which went back as far as 1962, they found just nine clinical trials that tested treatments for warts in a scientifically rigorous manner.
The treatments tested in these trials were cimetidine (a drug more often used to treat heartburn and ulcers), homeopathy (a form of alternative medicine), zinc sulphate (given as a liquid medication), and levamisole (a drug with various properties).
Reporting their findings in the Journal of Dermatologic Treatment, the researchers say that the strongest evidence was for zinc sulphate. Three separate trials compared zinc with an inactive sugar pill (placebo) and found that around seven out of 10 patients treated with zinc were cured of their warts, compared with just one out of 10 patients treated with placebo.
These results "suggest that zinc may hold promise in selected populations," say the researchers.
One study found that cimetidine was about twice as likely to cure warts as a matching placebo; however, cimetidine has potentially dangerous interactions with many other medications and can also cause unwanted side effects.
There was no evidence to support the effectiveness of levamisole or homeopathy, however.
"Limited evidence is emerging that zinc may be effective," conclude Drs Simonart and De Maertelaer. "Simple topical treatments containing salicylic acid should continue to be the mainstay of therapy for cutaneous warts."
MedWire (http://www.medwire-news.md/) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012
By Joanna Lyford