Insights into Tanning Biology and Tanning Products

This systematic review aims to critically assess the literature on the mechanisms of action, clinical uses, formulation strategies, and adverse effects of self-tanning agents, with a focus on dihydroxyacetone (DHA), melanotan, forskolin, and carotenoids.

A systematic literature review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were screened for relevance to the mechanisms of action, clinical applications, chemical formulations, or adverse effects of self-tanning molecules. A total of 68 peer-reviewed studies were included.

DHA induces pigmentation via the Maillard reaction and has demonstrated additional dermatologic applications, including use in vitiligo and erythropoietic protoporphyria and as a potential topical antifungal. Concerns persist about DHA-related cytotoxicity, genotoxicity, and systemic absorption. Unregulated melanotan I and II use has caused serious adverse effects, including rhabdomyolysis, renal infarction, and priapism. While forskolin stimulates melanin production independently of melanocortin receptors and has demonstrated efficacy in animal models, carotenoids, when ingested orally, accumulate in skin and subcutaneous fat, creating a yellow-orange hue. Both agents remain underresearched in human populations.

Limitations include lack of standardized reporting across included studies, variability in study outcomes, and limited long-term safety data.

Sunless tanning agents offer UV-free alternatives for cosmetic pigmentation but are not without risk. While DHA and melanotan remain the dominant agents in current use, forskolin and carotenoids offer alternative pathways for pigmentation and photoprotection. Further clinical studies are necessary to evaluate long-term safety, efficacy across skin types, and formulation optimization. Regulatory frameworks and dermatologic guidance must evolve to reflect the expanding landscape of sunless tanning modalities.