Squaric Acid Sensitization Therapy for Pediatric Warts

August 13, 2014

Squaric Acid Sensitization Therapy for Pediatric Warts

  1. Mary Wu Chang, MD

A retrospective analysis suggests that this treatment can be effective and safe when other treatments have failed.

  1. Mary Wu Chang, MD

Warts, caused by the human papilloma virus, are one of the most frequent complaints in the dermatologist's office, particularly in children. Cryotherapy or other painful procedures are difficult for the young child. Squaric acid dibutyl ester (SADBE) contact immunotherapy has been studied for alopecia areata since the 1970s but is less well researched for treating warts. Now, investigators have performed a retrospective chart review of 72 consecutive patients (age range, 3–18 years) treated with SADBE over a 10-year period in a pediatric dermatology clinic. All had recalcitrant warts. Many had failed conventional therapies, including salicylic acid, cantharidin, candida antigen immunotherapy, and imiquimod. Patients were sensitized with 2% SADBE on the upper volar arm under occlusion for one day. Two weeks later, parents applied 0.4% SADBE three times per week to the warts and gradually increased application frequency to daily to elicit a mild dermatitis. At monthly clinic visits, the concentration of SADBE was changed if needed.

Of 48 patients with obtainable treatment outcomes, 40 (83%) had complete wart resolution, 79% of whom used a maximum concentration of 0.4%. Average time to response was 2.6 months; mean treatment course of responsive patients was 8 months. Average follow-up was 34 months. Of 34 patients asked, 68% said they would do SADBE treatment again if needed. In 52 patients with safety data, adverse effects included erythema, pruritus, dermatitis, irritation, and blisters; 60% reported no adverse effects. Occurrence of adverse effects was unrelated to treatment response. Resolution rates were statistically the same in immunocompromised patients (4 of 5) and immunocompetent patients.


This large study, like previous case series, was uncontrolled; some of the improvement may have been placebo effect or spontaneous resolution. Nevertheless, the findings demonstrated safety and efficacy of home SADBE sensitization therapy for pediatric warts, even in immunocompromised patients. Treatment adherence affects efficacy, and office-based application may yield faster results. Home application with monthly doctor's appointments can be successful, but parents should not give up too soon, as 10 weeks of therapy may be needed to see a response.

Editor Disclosures at Time of Publication

  • Disclosures for Mary Wu Chang, MD at time of publication Consultant / Advisory board Pierre Fabre; Valeant Speaker’s bureau Galderma


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