What it is
Erythrulose is a tetrose sugar that reacts with amino acids in the outermost layer of the skin through the Maillard reaction to produce a gradual brown tint, the same general chemistry used by DHA. It develops more slowly than DHA and is often paired with it to give a more even, longer-lasting sunless tan. In a sunscreen-plus-bronzer product it provides cosmetic color rather than any UV protection.
Safety & warnings
Erythrulose is generally well tolerated topically and is not a recognized fragrance allergen or a comedogenic oil. As with all sunless tanners, the cosmetic color it produces offers no protection against UV exposure, so it should not be relied on for sun defense.
Origin & sourcing
A sugar that can be produced by fermentation or synthesis; it occurs naturally in small amounts in some foods.
History
Erythrulose was introduced into self-tanning products as a slower-developing partner to dihydroxyacetone (DHA) to improve color evenness and reduce the orange tones associated with DHA alone.
Questions everyone asks
How does erythrulose tan the skin?
It reacts with proteins in the surface layer of the skin to form brown pigments, creating a temporary tan that fades as those cells shed.
Does a tan from erythrulose protect against the sun?
No. The color is cosmetic only and provides no meaningful UV protection.