AHAs are one of the most well researched group of ingredients in skincare. Glycolic acid is a water-soluble alpha hydroxy acid (AHA) that is derived from sugar cane. It’s also one of the most well-known and widely used alpha-hydroxy acids in the skincare industry. So, why exactly is it so popular?

How does it work?
In low concentration (2-5%) glycolic acid is believed to facilitate progressive weakening of cohesion of the intercellular material of the stratum corneum (SC), resulting in uniform exfoliation of its outermost layers (the stratum disjunctum). Glycolic acid is incredibly effective at this type of chemical exfoliation because it has one key advantage over other AHA’s – it is a tiny molecule. And so can easily penetrate the skin.
The way the acid interacts with the layers of the skin is incredibly complex (and is still being researched) but one of the ways it helps your skin to look plumper and less dull is by speeding up cell turnover. It helps dissolve the bonds that hold skin cells together, allowing dead skin cells to slough off more rapidly than they would on their own. This also allows space for new cells to form.
Glycolic acid also stimulates your skin to create more collagen. Collagen is the protein that gives skin its firmness, plumpness, and elasticity. (Collagen is also the protein that gives strength to your bones and connective tissues.) As you age, collagen production naturally slows down. It’s also destroyed by excessive sun exposure. Using glycolic acid regularly can help prevent this breakdown of collagen.
What does it do for your skin?
Glycolic acid is a superstar ingredient because of it’s ability to chemically exfoliate the skin so well and so it is often used in anti-aging products because it can help smooth fine wrinkles and improve the skin’s tone and texture. It also plumps the skin and helps boost hydration levels.
It’s not just an anti-aging treatment, though, it’s often used to fade minor hyperpigmentation too. Because it’s an effective exfoliator, using glycolic acid regularly can help brighten the complexion. It’s this exfoliating property that also makes it an effective preventative against ingrown hairs. If you have large pores, glycolic acid can help make those appear smaller as well.
Many acne treatment products also contain glycolic acid. It isn’t an the most effective acne treatment, but glycolic acid can help keep pores clear from blockages, preventing comedones, blackheads, and inflamed breakouts from forming.
Although many sources claim glycolic acid gets rid of scars, that’s not entirely accurate. Glycolic acid can lighten dark discolorations left by acne or other wounds, and may soften the look of raised scars and pitted scars, but it will not make them disappear. For more efficient treatment, your best bet would be professional strength glycolic acid peels or a completely different scar treatment altogether.
Which one should you use?
The glycolic acid treatment you choose depends a lot on your skin type and what your end goals are. If you are simply wanting brighter, healthier-looking skin (or a reduction in breakouts and fine lines) an over-the-counter product is effective enough without stronger pro peels. Using low concentrations of glycolic acid over long periods of time creates a cumulative effect; your skin will look better the longer you use it.
For treating specific skin issues like noticeable sun damage, dark spots or acne marks, and deeper lines and wrinkles, or for marked improvement of the skin quickly, a professional peel is a good option. But because peels deliver a higher percentage of glycolic acid than daily use products they will be more irritating and have a greater chance of side effects.
When choosing any glycolic acid treatment, the percentage of glycolic acid is just one factor. The product’s pH is the other. A more acidic product will deliver a stronger and more effective treatment than a less acidic product, regardless of the percentage of glycolic acid. So a product containing a low percentage of glycolic acid but with a lower (i.e. more acidic) pH will be more effective than a high percentage but low acidity product.
Recommendations for OTC products
The Ordinary 7 Percent Glycolic Acid