Erythrulose works with free amino groups in your skin, like the sun, to stimulate your tan, and has the similar sun tanning kinetics to natural sunlight.

The tanning reaction takes place in the upper layers of the epidermis between the primary amino and imino groups of amino acids, peptides and proteins and the aldehyde or keto groups of self-tanning reducing sugar molecules. The resulting brown polymers are bound to proteins of the stratum corneum mainly via lysine side chains. The brown color is comparable to the appearance of a UV based suntan. The tanned appearance typically lasts from 2 to 10 days depending on application type, and skin condition.