In Dr. Vanderhooft’s experience, Candida antigen injections benefit some patients. After injection of 0.3 mL of Candida antigen into 1 or 2 warts at monthly intervals, researchers in one study observed complete clearance in 87% of patients after an average of 3.5 treatments, while 7% demonstrated no improvement after an average of 3.75 treatments (Pediatr. Dermatol. 2008; 25: 189-92).
Zinc supplementation is another option, she said. In a randomized trial, researchers who evaluated oral zinc supplementation versus placebo for two months found complete clearance in 20 out of 23 patients in the treatment group (87%), compared with none of the 20 patients in the placebo group (Br. J. Dermatol; 2002; 146[3]:423-31). All patients in the zinc group reported nausea. “That’s what has limited zinc therapy in my patient population,” Dr. Vanderhooft said.
In a more recent study, researchers conducted a placebo-controlled study of zinc sulfate 10 mg/kg per day up to 600 mg per day for up to two months (J. Am. Acad. Dermatol. 2009; 60[4]:706-8). Complete clearance of all warts was achieved in 78% of patients in the treatment group, compared with 13% in the placebo group. No recurrence of warts was observed at the six-month follow-up.
Topical 5-FU for warts has also been evaluated. One study of once or twice daily application of 5-FU under occlusion for 6 weeks demonstrated improvement in 88% of patients, including 13% with complete clearance (Br. J. Dermatol; 2011; 165[2]:233-46). No blood levels of the drug were detected. “It’s thought to be safe and well-tolerated, but over-the-counter salicylic acid has better efficacy and is quite a bit cheaper,” Dr. Vanderhooft said.
Another strategy for recalcitrant warts involves administration of squaric acid dibutyl ester. In a recent retrospective chart review conducted over a 10.5-year period, researchers evaluated 72 children with recalcitrant warts who had failed therapy with multiple agents and were followed for a period of 6 months to 11 years (Pediatr. Dermatol. 2015; 32:85-90). The protocol involved sensitizing the children to 2% squaric acid dibutyl ester (SADBE). The treatment then started two weeks later, with 0.4% SADBE applied 3 times per week initially, with an extra day added per week as tolerated to reach daily use if possible. The researchers found that 40 of the 48 (83%) patients in whom treatment outcomes could be obtained reported complete resolution of their warts. Seventy percent of patients used a maximum concentration of 0.4% SADBE and 60% of patients reported no adverse effects. The average time to reduction in size of warts was 2.6 months after sensitization, and treatment continued for a mean of 8 months.
Dr. Vanderhooft reported having no financial disclosures.