Interventions for Molluscum Contagiosum
Is there an effective treatment for molluscum contagiosum?
There is insufficient evidence to determine whether treatments for molluscum are effective.
Molluscum contagiosum, a poxvirus skin infection that largely affects children and adolescents, presents as single or multiple painless white papules with a central dimple. Lesions enlarge slowly and may reach a diameter of 0.2 to 0.4 inches (5 to 10 mm) in six to 12 weeks. After trauma, or spontaneously after several months, inflammatory changes result in the production of pus, crusting, and eventual destruction of the lesions. Most cases are self-limited and resolve within six to nine months. Treatments include cryotherapy, expression or pricking with a sterile needle, topical preparations (e.g., podofilox [Condylox], liquefied phenol, tretinoin [Retin-A], cantharidin, potassium hydroxide), and systemic treatment (e.g., cimetidine [Tagamet]).1
Five randomized controlled trials addressing the effectiveness of different topical treatments for raised molluscum lesions were identified. The participants included children, adolescents, and adults with molluscum. Immunocompromised patients and those with genital molluscum were excluded. The studies reported medium and long-term cure rates, time to cure, and adverse effects for the following treatments: povidone iodine plus salicylic acid (Keralyt); sodium nitrite plus salicylic acid; potassium hydroxide; systemic cimetidine; and calcarea carbonica (a homeopathic and impure form of calcium carbonate). No studies examined cryotherapy or needle expression. The included studies followed a total of 137 participants, with numbers of participants in each study ranging from 20 to 38. Overall, these studies were limited by small size and high drop-out rates, and some did not include an intention-to-treat analysis.
Only one study showed a statistically significant difference in the rate of complete cure in the treatment group. This study (n = 30) demonstrated that treatment with 5% sodium nitrite coapplied daily with 5% salicylic acid under occlusion resulted in a significantly higher rate of lesion cure after three months than treatment with salicylic acid alone (12 out of 16 participants [75 percent] compared with three out of 14 participants [21 percent], respectively [number needed to treat = 2]). The mean number of treatment days was lower in the treatment group than in the control group (38 versus 49 days, respectively). Adverse effects of the sodium nitrite plus salicylic acid treatment included brown staining of skin and irritation.
Another study (n = 35) found a shorter mean time to cure in the group treated with iodine plus salicylic acid plaster compared with iodine alone or salicylic plaster alone (26, 86, and 47 days, respectively). There was no significant difference in complete cure rates between the groups treated with 10% povidone iodine solution plus 50% salicylic acid plaster compared with povidone iodine alone (100 versus 60 percent [risk ratio = 1.67; 95% confidence interval, 0.81 to 3.41]). All participants developed redness of the skin at the treatment site within three to seven days after the start of the treatment.
The other three studies included in the review showed no significant difference in complete cure or lesion improvement with the use of topical 10% potassium hydroxide, systemic cimetidine, or calcarea carbonica compared with the placebo groups.
In the absence of evidence about treatment effectiveness, many experts recommend watchful waiting.1