What Are AHAs? Here's How Alpha Hydroxy Acids Help Skin Look Brighter & Clearer

Out of all the products I've tested out over the past few months, I noticed almost all my favorites contained the same key ingredients. Immediately after this realization, I was hit with yet another: Clearly, said ingredients were working for me, but I didn't really know what they were or how they worked. The ingredients in question are alpha hydroxy acids (AHAs), and if you've ever asked yourself, "What are AHAs and how do they benefit my skin?" I'm here with the answers.

For the record, when I say I'm here with the answers, I mean I've gotten the deets from a professional: Jennifer Chwalek, MD, a board-certified dermatologist at Union Square Laser Dermatology in NYC. She broke down exactly what AHAs were, and why they might be bringing about such drastic improvements for my skin. It seems like tons of popular skincare brands as of late are releasing AHA-laden products — Glossier, Drunk Elephant, and Farmacy, to name a few, but we'll get there later — so I figured it was about time I took a deep dive into what exactly I was applying on my face.

"AHAs, or Alpha Hydroxy Acids, refer to a class of chemical compounds (both naturally occurring and synthetic) used in cosmetics and chemical peels to exfoliate and improve dark spots, fine lines, wrinkles and overall skin texture," explains Dr. Chwalek. She gives examples including glycolic, lactic, citric, malic, tartaric, and mandelic acids, noting that glycolic and lactic acids are the most commonly used, and have the most research backing up their effects.

I admit, I am someone who naturally cringes at the thought of acid touching my skin — but in this case, it's totally different. So when you're applying AHAs to the skin, what exactly are they doing? "AHAs work primarily by exfoliating the skin," says Dr. Chwalek. "They dissolve the 'cement' between cells and allow the surface cells to shed." Think of a traditional scrub as a physical exfoliant, while AHAs are chemical exfoliants, targeting skin at the cellular level.

Leandro Crespi/Stocksy

This intense exfoliation helps with the anti-aging process as well, and sloughs off dead skin cells to leave skin looking brighter and feeling smoother. "As we age, the turnover of our skin cells decreases, causing our complexion to look dull," Dr. Chwalek explains. "AHAs, through their exfoliating power, can help maintain a more radiant complexion."

When it comes to aging, Dr. Chwalek also says AHAs work to target the physical signs of aging as well: "As AHAs penetrate the skin, they stimulate collagen production and can improve discoloration, as well as the appearance of the fine lines and wrinkles. How deeply an acid penetrates depends on the molecule size — for example, because glycolic acid has the smallest molecules, it is able to penetrate the deepest."

For me, AHAs have made the greatest difference in improving discoloration. I've noticed a significant lightening of my dark acne scars with regular use. Dr. Chwalek says that photodamage, sun spots or lentigines, post-inflammatory hyperpigmentation, and melasma can also be evened out.

If you aren't at the scarring stage of your acne journey, AHAs can still help out with your current blemishes: "They can also help acne breakouts and increase product absorption. For instance, using a topical antioxidant after a glycolic containing product like a wash can help to deliver the antioxidant deeper into the skin."

Me, pondering if AHAs are just too good to be true:

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According to Dr. Chwalek, anyone can use AHAs in their skincare routine, but the ideal users are those who struggle with acne, hyperpigmentation, sun damage, or signs of aging, like lines and wrinkles. However, she adds that precautions must be taken: "Because they can be irritating, they have to be used very carefully on individuals with rosacea, eczema, or sensitive skin, or for use on any skin that is irritated or has any cuts or burns."

So how will you know if you're too sensitive for regular AHA use? Well, there are a few side effects that you should be looking out for — and if you experience these, perhaps cool it on the AHAs: "The most common side effects are mild irritation, redness, flaking, itching, burning and, with higher concentrations, particularly in peels, you can have skin discoloration and, rarely, blistering," says Dr. Chwalek. "They can also potentially cause photosensitivity, especially if the skin is red and irritated from overuse, so using regular sun protection and moisturizers as needed while using AHAs is important."

Proceeding with caution, Dr. Chwalek recommends using products with no more than 10 to 15 percent AHA on a daily basis. Only one product per routine is necessary, because while appropriate use can get you a brighter, more even complexion, overuse can trigger irritation. After seeing lots of success using AHA products, I've been tempted myself to overdo it, in hopes of more dramatic results, but after hearing Dr. Chwalek's warnings, I'll definitely stick to my current routine of incorporating AHAs a few times a week — at most.

And what exactly am I using, you ask? These are some of the products I find effective yet gentle enough to use on an almost daily basis (not all together of course, but one per day) and keep on overnight:

Farmacy; Glossier; Beautycounter

First up is the Farmacy Honeymoon Glow AHA Resurfacing Night Serum ($58, farmacy.com). It's my only true AHA serum, and it contains a 14 percent AHA/BHA/flower acids blend, along with hyaluronic acid and honey to make sure skin stays hydrated and isn't dried out by the powerful acids.

If you're wondering what BHAs are (we're throwing a lot of letters around, here), they're beta hydroxy acids. BHAs are also great for exfoliation, often coupled with AHAs, and especially good for use on anyone with oily skin. When this product is in my lineup, I use it every other night in place of a traditional serum, and it sometimes tingles as I press it into my skin, which I sort of love because it really feels like it's working.

The Glossier Solution Exfoliating Skin Perfector ($24, glossier.com) is the most reasonably priced product containing AHAs I've ever come across, and for that reason, I had to give it a go. This one is great for daily use, though it might take you a few weeks to build up to it, as everyone's skin is different, and mine is fairly tough. The solution contains a 10 percent blend of AHAs, BHAs, and PHAs, the latter of which are polyhydroxy acids. I noticed my skin texture getting smoother within just a week of daily use, so this has definitely become a permanent fixture in my skincare cabinet. I put one or two pumps of product onto a cotton pad and wipe it all around my face after cleansing, focusing on my particularly congested areas.

My Beautycounter Overnight Resurfacing Peel ($58, beautycounter.com) has become a go-to nighttime treatment for me after days where I've worn a ton of makeup, traveled around, or just given my skin a tough day in general. Don't freak out over the word "peel" — your skin will not peel off! Instead, 15 botanically derived acids work together in an AHA/BHA combo to clean up your skin while you sleep, diminish the look of fine lines, tighten pores, and reduce dark spots.

Since there are soothing acids included along with the more extreme ones like glycolic, lactic and malic acids, the product is balanced enough that you won't wake up feeling too dry or tight. Putting this on my skin after a long day makes me feel like I'm doing something good for it, and I'm able to use it quite a few days in a row consistently with no issues.

When my skin is really acting up, I'll occasionally go for either of these two powerhouse AHA masks to get it back in line:

Drunk Elephant; Shiffa

When I'm unexpectedly breaking out, the Drunk Elephant T.L.C. Sukari Babyfacial ($80, drunkelephant.com) is the only thing that will do. I'll use it once that week and find it really purges my skin in a safe, healthy way. Any breakouts sitting under the skin are brought to the surface quickly, and while I might be more pimple-covered than before the next day, the zits are instantly extraction-ready. A day or two later, my clear skin is restored.

It does tingle while I apply it and when I wash it off after, and it can be a teeny bit painful if I've got active acne, but it always gets the job done, and that's why I swear by it. This resurfacing miracle contains a whopping 25 percent AHAs and 2 percent BHAs to really target the pore lining as it exfoliates dead skin cells. Even though it's quite a splurge, I consider this an absolute essential for anyone who regularly breaks out.

Finally, my other go-to for weeks when I need a more thorough resurfacing for my skin is the Shiffa Tri-Acid Radiance Peel ($71, shiffa.com). This guy contains glycolic, lactic, and salicylic acids to banish dullness and eliminate dead skin cells, but it comes coupled with marine extracts and brightening essential oils to plump up the new skin that's revealed post-exfoliation. Like the Drunk Elephant mask, I leave this one on for about 10 minutes before washing it off and use it just once a week, twice at most if I'm really struggling.

Keep in mind, everyone's skin is different, and while some of these products suit me personally for everyday use, the proper way to begin using AHAs frequently is to start small and work your way up, based on skin sensitivity. If you're desperate for a powerful ingredient to transform your complexion, I highly suggest incorporating AHAs into your routine, and I'll keep my fingers crossed that you experience the same brightening, smoothing, and rejuvenating results I've been #blessed with, too.