DHA (Dihydroxyacetone)

Dihydroxyacetone (DHA) is the FDA-approved active ingredient in nearly every professional spray tan solution. It is a 3-carbon sugar derived from sugar beets and sugar cane that undergoes the Maillard reaction with amino acids on the outermost layer of skin (the stratum corneum), producing melanoidins — the same family of brown compounds responsible for the color of toasted bread crust. The reaction begins within minutes of application and continues developing for 4–10 hours. DHA concentration determines tan depth: light solutions are 6–8% DHA, medium 8–10%, dark 10–12%, and rapid-development or competition solutions reach 12–14% or higher. The FDA permits topical use of DHA but explicitly cautions against inhalation, ingestion, and application to mucous membranes (lips, nose, eyes) — which is why professional spray tan studios provide nose plugs, lip balm, and eye protection. DHA does not provide UV protection, does not damage skin DNA, and is not absorbed in significant quantities through intact skin. Tan fades over 7–10 days as the stratum corneum naturally exfoliates. Per FDA guidance, DHA is generally recognized as safe for external application but should not be used in tanning booths that allow inhalation.