Successful treatment of periungual warts is clinically challenging, as many are refractory or represented after conventional therapies. Using destructive therapies, like cryotherapy, may even result in permanent nail dystrophy. A recent series of nine cases in which intralesional cidofovir was used for recalcitrant periungual warts (mean of 2.7 treatments) showed: 

• Improvement in the appearance of warts in 100% of patients.
• Near to complete resolution in 77.8% of the patients.
• Reports of few self-resolving local reactions, including pain, edema, erosion, blister formation and discoloration at the proximal nail fold.
• Resolution of all reactions within weeks of treatment and requirements of no additional treatment. 

This study shows that intralesional cidofovir treatment of recalcitrant periungual warts is well-tolerated and provides unmatched results. The risks of traditional therapies to the nail direct the use of intralesional cidofovir as a first-line therapy for periungual warts. Randomized clinical trials in the future are necessary to demonstrate the effectiveness of intralesional cidofovir.

Source: Poppens M, Davis J. Intralesional cidofovir for the treatment of recalcitrant periungual warts. J Dermatolog Treat. 2022 Dec 1:1-10.