DL-Mandelic acid, also known as mandelic acid (originally extracted from bitter almonds), is a kind of high molecular weight fruit acid that can accelerate the metabolism of skin cells, has an exfoliating effect, helps reduce fine lines, and clears deposits on the stratum corneum. The melanin in the cells improves pigmentation and has a whitening effect (it can be used to fade acne marks). But the effect is slightly inferior to glycolic acid, because mandelic acid has a large molecular weight and weak permeability. Mandelic acid is lipophilic. Compared with common fruit acid-glycolic acid, mandelic acid has certain antibacterial ability. At the same time, compared with the common glycolic acid and lactic acid, the penetration rate of mandelic acid may be slower, which means that the irritation is less than that of glycolic acid. Its fat solubility increases, and the stratum corneum penetration ability is improved. Therefore, glycolic acid can also dredge the oil in the pores and play a role in removing acne. Like glycolic acid and lactic acid, mandelic acid also has a certain whitening effect.