Cantharidin in a collodion vehicle has been used by dermatologists as a treatment for molluscum contagiosum and warts since the 1950s. Cantharidin lost FDA approval in 1962 because its manufacturers failed to submit data attesting to cantharidin's efficacy. However, in 1999, the FDA included cantharidin on its "Bulk Substances List" of drugs which although not available as commercial products, were approved for compounding on a customized basis for individual patients.

Because of cantharidin's potential for toxicity, the FDA has proposed that cantharidin should be limited to "topical use in the professional office setting only." Severe blistering can result from improper use, and ingestion, especially by children, can be fatal. Treatment of mucous membranes is contraindicated and placement of cantharidin near the eyes and eyelids should be avoided to prevent scleral erosion.

Caution: The treatment of plantar warts with cantharidin is NOT recommended and may have a higher rate of significant complications including lymphangitis and refractory lymphedema.

Arch Dermatol. 2001;137:1357-1360
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J Am Acad Dermatol. 2000;43:503-507
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Squaric Acid Dibutylester (SADBE) for Cutaneous Warts in Children

Warts are a common pediatric skin infection and clearance may be enhanced by contact sensitizers, such as squaric acid dibutylester (SADBE). Contact immunotherapy with SADBE is relatively safe and an effective alternative in the management of multiple and resistant cutaneous warts in children.

J Am Acad Dermatol. 2000 May;42(5 Pt 1):803-8
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Pediatr Dermatol. 2000 Jul-Aug;17(4):315-8
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Oct;41(4):595-9
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