Intralesional Cidofovir Promising for Refractory Warts

SEATTLE — A case series of children aged 7-17 years found that treatment with intralesional cidofovir was effective in healing recalcitrant warts, with several children experiencing complete resolution.

The results were presented in a poster session at the Society for Pediatric Dermatology (SPD) 2025 Annual Meeting.

“Treatment was well tolerated, and we were able to control pain,” study author Vivian Iloabuchi, BS, a third-year medical student at the Mayo Clinic Alix School of Medicine in Scottsdale, Arizona, told Medscape Medical News.

Cutaneous warts, caused by human papillomavirus, are fairly common in children and adolescents. While they often resolve spontaneously, regardless of treatment, some can be persistent and may be refractory to standard therapies. Despite the many treatment options available, including salicylic acid, Candida antigen injections, cryotherapy, and topical immunotherapy, none have been established as curative, and treatment of refractory warts can be challenging.

Previous research suggested that off-label use of intralesional cidofovir, an antiviral drug approved to treat cytomegalovirus retinitis, may be effective in treating recalcitrant cutaneous warts. A retrospective analysis of 58 children and adults, down to age 10 years, which included immunocompromised patients, found that after a mean of 3.4 treatments of intralesional cidofovir, 98% of warts improved and 76% resolved completely. A case series of nine adults showed similar efficacy, with 77.8% of patients achieving near-complete resolution of recalcitrant periungual warts after treatment with intralesional cidofovir (mean, 2.7 treatments), with minimal side effects. The appearance of warts improved in all the patients.

Cidofovir is not intended to be a first-line treatment, and all patients had received standard therapies previously, Iloabuchi said.

Study Details

The results reported at the SPD meeting were from a case series of seven children aged 7-17 years with three or more cutaneous warts located on the extremities that had not responded to salicylic acid, cryotherapy, Candida antigen injections, oral cimetidine, and/or pulsed dye laser.

Cidofovir 15 mg/mL was injected into each wart, at doses ranging from 2 mg to 13.5 mg, with a total dose per session from 4.5 mg to 30 mg. Six of the patients required pain control during the procedure (lidocaine in four patients, application of ice in one patient, and the use of a Buzzy device and topical vapocoolant in one patient). In this group, three patients achieved complete resolution of warts after two treatment sessions.

In one patient with warts on both hands, the warts on one hand resolved after five treatments, but the patient experienced a recurrence. After eight more sessions, the warts improved but did not fully resolve. Two patients were lost to follow-up after one session, and one patient declined further treatment after one session with no improvement.

The authors noted that this case series lends support to the growing body of evidence showing that intralesional cidofovir can be a treatment option for recalcitrant warts in a pediatric population.

While the results are encouraging, “we do need larger studies with more patients and longer follow-up,” Iloabuchi said.

Asked to comment, Luke S. Johnson, MD, associate professor in the Department of Dermatology at the University of Utah, Salt Lake City, agreed that these results provide more evidence to support intralesional cidofovir for this indication. “Anecdotally, some of my colleagues are using this in adults with decent success,” said Johnson, who was not involved in the study. “Obtaining it is the trick — and it can be expensive. And to my knowledge, it has not been compared to topical cidofovir.”

Noting that “head-to-head studies are pretty uncommon in our world,” he said, “I would use it if I could get it and be reimbursed for it.”

The study was independently supported. Iloabachi reported having no relevant financial relationships. Johnson had no relevant disclosures.

Roxanne Nelson is a registered nurse and an award-winning medical writer who has written for many major news outlets and is a regular contributor to Medscape Medical News.