The Difference Between Glycolic Acid, Hyaluronic Acid & More

Navigating the confusing world of skin-care ingredients can lead us deep into the depths of Google trying to figure out what works, what doesn’t, and why high school chemistry didn’t prepare us for any this. One thing we do remember from lab experiments, though? Acids. When used in skin care, these are the exfoliating ingredients that make skin fresh and glowy, and can treat and even prevent acne, wrinkles, and spots.
“Acids can dissolve skin cells, and when you [use them] in a small dose, [they] will take off the dead skin layer to give you brighter, smoother skin,” explains Manhattan dermatologist Macrene Alexiades, MD, of Dermatology and Laser Surgery Center of New York. “Other acids can also penetrate into the hair follicle to help break up the buildup that causes acne or get between skin cells for anti-aging.”
The trick is finding exactly the right acid and product type — cleanser, mask, serum — for your skin type, as sensitive, acneic, oily, dry, and combination skin all benefit best from different ingredients. Ahead, your guide to which acids will work best for your skin type.
Important tip: No matter your skin type or the product, always do a patch test somewhere discreet, like on your neck near your ear, to see how your skin reacts first.
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This is the trickiest skin type when it comes to acids. When used incorrectly or too aggressively, they can trigger irritation and redness. The first rule of thumb, says Dr. Alexiades, is to look for products with fewer active ingredients. “You don’t want to go with a mixture of several types of acids blended into one product or you’ll get into trouble,” she says. “Even a mixture of fruit acids, which sound benign, can be too much.” Another word of advice: Look for the ingredients in moisturizing creams or lotions where the acid will be more diluted and in a gentler formulation.
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While glycolic acid can be one of the most effective (and sometimes harsh) acids, look for formulas with a “buffered” version of the ingredient. “This means that the acid is not free to act, but is mixed within a solution that acts as a barrier between the acid and the skin,” explains Dr. Alexiades. “Basically, it acts more slowly.”
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Choose peeling agents that have more moisturizing acids in them. “Lactobionic acid and gluconic acids are actually cousins to glycolic acid, but they draw in moisture and water molecules, so they are very hydrating while they exfoliate,” says Dr. Alexiades.
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One of the skin types that can see the most improvement from acids is pimple-prone skin, because the exfoliating and dissolving properties of certain acids help keep pores open and clear. That doesn’t mean that more is more, however, as acne can worsen if over-treated. Instead, use acids that also have antibacterial and anti-sebum properties, recommends Dr. Alexiades.
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“Mandelic acid is excellent for acne and acne blemishes,” says Dr. Alexiades. The bitter almond-derived ingredient is famous for keeping pores unclogged and preventing acne when used regularly over a long period, not just when you’re struggling with a breakout.

Vivant Skin Care Mandelic Acid 3-in-1 Wash, $40, available at Dermstore.
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“With normal skin, you can...go all out,” say Dr. Alexiades. What she means by that is that normal skin types can try combinations of acids that are blended together, which often treat the skin more aggressively to prevent aging as well as acne, in addition to keeping your skin looking healthy.
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Look for peels and masks with a blend of alpha, beta, and/or polyhydroxy acids together. Wipes make application super easy. Try using a blended peel once a week and, if you find your skin can tolerate it, build up to once daily use.
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“Citric acid is a well-tolerated, all-around friendly acid for normal skin and has great brightening effects,” says Dr. Alexiades. That means that not only will your skin feel soft and smooth, it will also have that pretty, even-toned radiance that we’re always trying to fake with strategic highlighter. Bonus benefit: The antioxidant power of citric acid neutralizes damaging free radicals.
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Much like sensitive skin, dry skin can react poorly to harsher acids, so tread carefully. Dry skin often has what’s called a “compromised barrier,” which means the layer of lipid molecules that help seal in moisture are already lacking. The good news is a number of acids also have hydration-attracting properties, making them ideal for dry types.
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You’ve probably been hearing a lot about hyaluronic acid lately. While technically this popular ingredient isn’t an acid quite like the rest (it doesn’t dissolve skin cells away), HA is an amazing humectant, meaning it attracts water to skin. In fact, an HA molecule can famously attract 1000 times its own weight in water.
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“Look for acids that incorporate humectants that draw in water molecules,” advises Dr. Alexiades. “Gluconolactone is a good example: It moisturizes as it provides the acid peel, giving you the best of both worlds.”
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If you have packets of oil blotting papers in your desk and bag, you’ll be happy to learn that the right acids can help keep sebum production under control. You’ve probably heard this before, but it bears repeating: If you sap oily skin of all its moisture, the skin responds by sending even more oil up to the surface, which creates a vicious cycle. That's why it’s key to find acids that reduce oil without completely purging the skin of any moisture.
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Lactic acid is derived from fruit, vegetables, and other plants, but it also comes from milk. (Cleopatra was ahead of the game with her milk baths.) The acid is gentle yet effectively exfoliates the skin. “Patients with chronically oily skin do best with lactic acid,” says Dr. Alexiades. “It gives a good balance of oil control without overdrying the skin.”
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Mandelic acid, also great for acne-prone skin, is an oil soluble acid, which is why it can get down into your pores to break up sebum and help regulate its production.
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While unfortunately no acid will give you a “big reveal” moment where you peel away spots and lift and tighten skin all at once, acids can give immediate and long-term benefits for smoother, younger-looking skin. “Keep in mind, no anti-ager will be able to work unless you’re also using sunscreen to protect the progress the cream makes,” warns Dr. Alexiades. Plus, exfoliation can make skin more likely to burn, so be sure to wear SPF 30 daily and reapply.
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“Ascorbic acid is a form of vitamin C, which has a long track record for treating skin aging,” says Dr. Alexiades. Out of all the research on how vitamin C counteracts signs of aging, the most research has been on ascorbic acid, which is sometimes listed on the label as L-ascorbic acid, as well. Studies have shown it helps reduces wrinkles, spots, and is also one of the more potent antioxidants you can wear on a daily basis to shield skin from the damage caused by pollution, sun, and other outside aggressors.
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Amino acids and amino acid derivatives can lighten brown spots and are considered the early building blocks of collagen production to keep skin plump and smooth. Look for a product with multiple amino acids all in one formula.
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