Topical Cantharidin Safe and Effective for Warts and Molluscum Contagiosum
Cantharidin is a natural toxin extracted from blister beetles which is used to warts and molluscum contagiosum.
Topical cantharidin showed high efficacy and safety for the treatment of warts, especially when used with podophyllotoxin and salicylic acid, according to research published in the American Journal of Clinical Dermatology. The same therapeutic combination provided modest benefit in cases of pediatric molluscum contagiosum (MC), in spite of good tolerability and safety.
Study investigators performed a systematic review of the available literature and research in regard to the treatment of MC or warts with topical cantharidin. Researchers reviewed data from clinical trials and cohort, cross-sectional, and observational studies from several different dermatology databases. The 20 studies reviewed included data from 1958 through 2018 for 1752 men and women aged 0.3 to 62 years.
For treatment of MC, clearance rates varied (15.4% to 100%). Treatment for warts demonstrated significant clearance and maintenance of clearance with use of topical cantharidin monotherapy. The use of topical cantharidin in combination with other agents, such as podophyllotoxin and salicylic acid, demonstrated efficacy for treatment of plantar warts in adults and children, with a clearance rate range between 81% and 100%. In most cases, clearance required only one treatment. Cantharidin therapy was reported to be well tolerated, with minor adverse events that included pain (7% to 85.7%), blistering (10% to 100%), and pigmentation changes (1.8% to 53.3%).
The systematic review had some limitations, such as an overall low level of evidence among the studies reviewed. Most of the studies reviewed were retrospective and did not include comparison groups. Reports also included a lack of data on patient follow-up.
Investigators conclude that topical treatment for warts with cantharidin is effective, safe, and well tolerated among patients. Topical treatment of plantar warts with compounds that include cantharidin and podophyllotoxin and salicylic acid consistently demonstrated 100% clearance rates across studies. Topical treatment of MC with cantharidin as a monotherapy demonstrated variable efficacy but was well tolerated and had good treatment satisfaction among patients. Further research is needed to determine optimal techniques and regimens for use in clinical settings.
Vakharia PP, Chopra R, Silverberg NB, Silverberg J. Efficacy and safety of topical cantharidin treatment for molluscum contagiosum and warts: a systematic review [published online August 10, 2018]. Am J Clin Dermatol. doi: 10.1007/s40257-018-0375-4.