What is AHA?Updated a year ago
AHA stands for alpha hydroxy acid, which is a category of water-soluble chemical exfoliants.
Before you run away from AHAs because they’re “chemicals,” remember that water is a chemical. Heck, your body is made of chemicals! Chemicals are just any pure substance with a “defined” composition.
Other chemicals you encounter in your day-to-day life include the oxygen you breathe, the salt on your table, and the vitamin C in your fruits, veggies, and maybe even skin care. AHAs are very specific and gentle chemicals that happen to be exactly what the surface of your skin needs to renew itself.
Exfoliation, of course, is the process of removing dead skin cells from the very surface of the skin. It’s essential for maintaining skin smoothness, improving hydration, and helping leave-on skincare products penetrate into the skin.
There are a lot of AHAs out there. If you’re into skincare, chances are you’ve heard about glycolic and lactic acids, which are the two main AHAs used in skincare.
Glycolic Acid
Glycolic acid has been used in skincare for decades. It’s almost up there with retinol for its incredible effect on skin smoothness, texture, and luminosity, and yet, it doesn’t get nearly the level of adoration it deserves.
When it comes to skin impact, it’s the smallest of the AHAs and therefore also the most intense (but not too intense, as we’ll get into soon). In skin care, tiny is mighty.
Smaller molecules penetrate the surface of the stratum corneum with ease (that’s the outermost layer of the epidermis, which is composed entirely of dead skin cells). This allows them to act on the skin more deeply and thoroughly.
As we’ll soon discuss in more detail, it has been extensively researched not just for its exfoliative power, but also for its ability to slow visible skin aging and amplify the renewing power of retinoids.
Lactic Acid
Lactic acid is the gentler of the two main AHAs, thanks to its slightly larger molecular structure. While it’s not quite as potent or exfoliative as glycolic acid, it’s skin-identical. That means that it naturally exists in human skin (especially when we’re young). It helps to keep the skin moist while also aiding with the natural desquamation (i.e. cell-shedding) process.
It’s often recommended for those with sensitive skin, but we find that combining glycolic and lactic acids provides the skin with a more diverse exfoliative footprint. It’s an ideal way of enhancing the exfoliation abilities of a formula without resorting to levels of glycolic acid that could irritate sensitive skin.