Exothermic Heat Patch Safe and Effective for Treatment of Warts

An exothermic heat patch that emits a constant temperature of ~42°C applied to the surface of a wart for 2 hours daily for 12 weeks resulted in clinical clearance in around 50% of participants.

An exothermic heat patch that may produce a systemic response leading to the resolution of warts could be a safe treatment option for warts, according to a study published in Journal of Drugs in Dermatology.

In this uncontrolled, open-label, proof-of-concept study, investigators evaluated the safety and efficacy of a novel epicutaneous heat patch for the treatment of warts. Participants in the study had presented with at least 2 warts (N=15), in which 1 was considered the target and the other as the untreated control; only the target received the heat patch treatment while the control was observed and measured. The mean size of the target wart was 4.6 x 3.2 mm, while the mean size of the control wart was 3.6 x 2.4 mm. The heat patch was placed in a vacuum-sealed pouch and contained a mixture of chemicals including ferric chloride, which reacts with atmospheric oxygen to generate reproducible, rapid exothermic warming of the skin. The heat is believed to alter the immune system response and eliminate human papillomavirus in wart tissue.

Participants applied the heat patch for a minimum of 2 hours daily for 3 months. Warts were evaluated at weeks 2, 4, 8, and 12 with digital photos and measurements of the longest diameter of each wart. Treatment intervention ended at 12 weeks, and follow-up visits were conducted at weeks 18 and 24.

Two end points for efficacy were measured at weeks 12 and 24, at which time investigators determined the percentage of participants who achieved at least 50% decrease in investigator global assessment (IGA) score and complete clearance (100% IGA score) for their treated warts. By week 12, 42.9% of target warts decreased in size by more than 50%, and 28.6% achieved complete clearance prior to control warts. By week 24, 53.3% of the target warts had decreased in size by more than 50%, and 46.7% had achieved complete clearance.

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This study was limited by the small sample size, but it is the largest study of epicutaneous heat patches in the treatment of warts.

The researchers suggest there is an immunological mechanism of action of local hyperthermia and that perhaps there are factors beyond those in the local environment induced by this hyperthermia comparable to those of immunotherapy with skin test antigens. More studies are needed to confirm this hypothesis.

Disclosure: This study was funded by Ferndale Pharma Group, Inc. Israel Dvoretzky, MD, and Richard J. Antaya, MD, are consultants for Ferndale Pharma Group, Inc.

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Antaya RJ, del Carmen Fraile Alonso M, Sukumar N, Li FY, Dvoretzky I. An open label study of an occlusive heat patch in the treatment of warts. J Drugs Dermatol. 2019;18(4):368-373.