Topical application of octyl salicylate or homosalate results in limited skin penetration [86,117,118], which is consistent with findings from skin permeability studies of other lipophilic UV filters. The study by Walters and colleagues is the most thorough study of the dermal penetration of octyl salicylate. The most thorough study of the dermal penetration of octyl salicylate was done by Walters and colleagues [117]. In this study [117], the authors reported that less than 1% of the administered dose of octyl salicylate penetrated human skin. This is similar to the skin penetration of homosalate. These two compounds are expected to be metabolized by cleavage of the ester bond, yielding salicylic acid and octyl and trimethylcyclohexyl moieties. Therefore, any systemic effects are limited and consistent with salicylic acid toxicity.
Studies published in JAMA by Matta et al. (May 2019 and January 2020) measured plasma concentrations of UVF formulations used under homosalate conditions of maximum use to meet JAMA regulations time and scope application (TEA) process. FDA 2011 Final Rule (Wang et al., 2011; Narla and Lim, 2020). These studies showed that seven commercially available UVF ingredients (avobenzone, oxybenzone, octocrylene, homosalate, octyl salicylate, octanolate, and ecamsule) were absorbed systemically and made headlines News and social media. The authors make it clear that their findings provide no evidence of systemic toxicity (more on this below) and therefore should not discourage sunscreen use. However, patients may question "are these products causing some harm"...maybe even "do more harm than good?" Could the protective products they have carefully used for themselves and their families have unintended adverse effects on their health? In response, the AAD re-emphasized that sunscreens are only one part of an overall "Safe Sun Protection Program" and that these products have been used for decades to reduce the risk of skin cancer without any reported internal side effects