Both alpha-hydroxy acids and beta-hydroxy acids (AHAs and BHAs) can help fade dark spots. They’re different products, but they function in a similar way. AHAs, like lactic acid, glycolic acid, and mandelic acid, for example, help lighten dark spots by simply exfoliating the skin, Suarez says. “They can be irritating, however, and the irritation can worsen some types of [inflammation], especially in deeper skin tones,” she continues.
If your skin is a bit more sensitive to AHAs, consider opting for mandelic rather than glycolic or lactic acids. This ingredient is more gentle but will still help fade dark spots over time. In fact, a skin care regimen containing mandelic acid and vitamin C was associated with a 73% improvement in the appearance of post-inflammatory hyperpigmentation and melasma.
BHAs, like salicylic acid, are traditionally used to treat acne but can be used to lighten dark spots, especially those from post-inflammatory hyperpigmentation. “It does so by exfoliating the skin, but it also is anti-inflammatory,” Suarez says. “Because of its structure, it favors oily areas, like the T-zone.”