Effective Topical Treatments for Nongenital Warts
What is the best topical treatment for cutaneous nongenital warts?
Topical salicylic or lactic acid and cryotherapy are effective treatments for nongenital warts. Although cryotherapy is somewhat more effective, it is associated with more pain and blistering than salicylic or lactic acid. The spontaneous cure rate of nongenital warts is 50 to 70 percent after three months; therefore, no treatment should always be presented to patients as a valid option.
Cutaneous nongenital warts are caused by the human papillomavirus. Although these warts are not dangerous, they are unsightly and may be uncomfortable. Therefore, patients often seek treatment from their primary care physician. There are a variety of topical treatments for nongenital warts. Although salicylic acid, lactic acid, and cryotherapy are used most often, some physicians use podophyllin, fluorouracil, glutaraldehyde, or formaldehyde for the treatment of resistant warts.
This Cochrane review included randomized controlled trials of topical treatments for warts. Five trials (322 total patients) compared six to 12 weeks of treatment with salicylic or lactic acid with placebo. Active treatment had a significantly higher cure rate than placebo (73 versus 48 percent; number needed to treat [NNT] = 4; 95% confidence interval [CI], 3 to 7). Only two poor-quality studies compared cryotherapy with placebo. Although no significant difference was found, one study found an unusually low cure rate (9 percent) with cryotherapy, and the other study found an unusually high cure rate (40 percent) with placebo.
Comparisons of aggressive and gentle cryotherapy regimens (e.g., two minutes versus 15 seconds or double versus single freezes) found that aggressive cryotherapy is more effective than gentle cryotherapy (52 versus 31 percent; NNT = 5; 95% CI, 3 to 7). However, in one study of more than 200 patients, aggressive freezing caused more pain and blistering (64 versus 44 percent; number needed to harm = 5; 95% CI, 3 to 15).
The three studies that compared different freezing intervals found no difference in cure rates with two-, three-, or four-week intervals. Two studies comparing salicylic or lactic acid with cryotherapy found no significant difference among the therapies, although they found a trend toward greater benefit with combined therapy than with salicylic or lactic acid alone.
There was insufficient or limited evidence for the effectiveness of intralesional bleomycin (Blenoxane), topical fluorouracil, intralesional interferons, topical dinitrochlorobenzene, photodynamic therapy, and pulsed dye laser. These therapies are not recommended because of their cost, complexity, and possible toxicity. No practice guidelines on this topic were identified in the National Guideline Clearinghouse.