Also known as vitamin C, ascorbic acid is "one of the most potent antioxidants for skin," Gohara says. "It's good for daily use to help fight damage from pollution and UV light. It also helps with fine lines, and can even out your complexion and overall skin texture." Additionally, the ingredient is known for its ability to combat dark spots and hyperpigmentation.
Lorencin notes that it can be especially effective when used in conjunction with retinol or hyaluronic acid. Though be sure to use caution: "It's great for most skin types, but it can be irritating to sensitive skin, especially if you're prone to rashes," she says.
"Polyhydroxy acids are a newer generation of alpha hydroxy acids," explains Guanche. "They are milder and less irritating (or stingy) when applied, but they still micro-exfoliate the skin." Since it's a larger molecule, PHAs are able to "remove the surface of dead skin cell layers without penetrating too deeply in the skin," which translates to less irritation, explains Guanche. She also notes that they're great for improving pigment, fine lines and even hydration (thanks to the fact that it's also a humectant).
Also, its gentleness makes it great for sensitive skin: "It's especially good for skin prone to rosacea and eczema and mature compromised complexions," says Lorencin.
You'll often see ferulic acid used in conjunction with vitamins C and E. "Vitamin C especially tends to be unstable in formulation, but the ferulic acid helps it maintain stability," Guanche says. "It has antioxidant effects and reduces damage caused to the skin by free radicals."
Azelaic acid is becoming more and more popular as a skin care ingredient lately, which is in part due to its effectiveness in treating "acne, rosacea and unwanted pigmentation," Guanche says. She also notes that the exfoliating acid is great for helping eradicate any mites you may have in your pores (yikes!). Similarly, Lorencin says that "it is especially effective in fighting P. Acnes bacteria," (aka one of the main causes of acne). "It is milder than salicylic acid and can be tolerated by most skin types," she adds.
