Is It OK to Use Acids in Your Skincare Routine During the Summer?

We’re breaking down what’s safe and what isn’t

If you’ve dealt with problematic skin of any kind this summer—whether it’s due to maskne, milia caused by too-thick moisturizers or stress-induced zits and dullness—then you probably already have certain acids, found in chemical exfoliants, on your radar. These holy grail ingredients, like salicylic acid, glycolic acid and lactic acid (just to name a few) are often recommended as no-brainers when it comes to a huge range of skin concerns. Feeling like your pores are congested? Glycolic acid! Got blackheads? Salicylic acid to the rescue. Skin looking dull? Make lactic acid your best friend.

That being said, you’ve likely also heard that with these popular skincare recommendations comes the reminder that these ingredients can make your skin more sensitive to the sun, and thus more susceptible to the damaging effects of its UV rays. You’ll also see it in the usage directions on the packaging of products containing AHAs (alpha hydroxy acids like glycolic and lactic acid) and BHAs (beta hydroxy acids like salicylic acid).

So what can be made of lesser known studies that occasionally pop up (such as this article) that claim that glycolic acid might actually have the opposite effect—that it is photoprotective and antiinflammatory, and actually provides skin with some protection from the sun? We reached out to chemist and skincare and cosmetic formulator Stephen Alain Ko to set the record straight. Read on to learn the facts about using acids in your skincare routine during the summer, so you can make sure you’re adequately protecting your skin.

First things first: Do chemical exfoliants actually weaken your skin?

Technically, they thin your skin, but it’s not nearly as intense as it sounds. “Exfoliants can thin the stratum corneum,” says Ko. But that’s just the top layer of dead skin cells. While this can weaken some of its protective barrier effects, explains Ko, AHAs can actually increase the water content of your skin, as well as the production of collagen, elastin and glycosaminoglycans (your body’s natural moisturizers, such as hyaluronic acid), with continued use, these ingredients can actually lead to increased skin thickness.

What about making you more susceptible to sun damage?

Ko says that “experiments reviewed by the Cosmetics Ingredient Review (CIR) have shown that over time, topical application of AHAs can increase the sensitivity of the skin to UV damage.” (This is determined by measuring sunburn cells.) That’s why the FDA recommends wearing sunscreen when using products formulated with AHAs—although you really should be wearing sunscreen every day, regardless of what other steps are in your routine. “It’s also important to remember that sunscreen is just one method of photoprotection,” suggests Ko. “Seeking shade, protective clothing and reducing exposure to the sun are also important methods.”

That being said, “with proper use and moderation, [the use of chemical exfoliants is not only] fine but can result in the removal of dry, rough and scaly skin, [contributing to] a smoother appearance,” says Ko.

Are there any acids that should be avoided in the summer?

“For products that people can buy in stores and online, not necessarily,” says Ko. (In Canada, the maximum percentage of acids allowed in over-the-counter formulas is 30%.) “However if someone is receiving a chemical peel from a professional or a doctor, then it would be best to heed their recommendations.”

Ascorbic acid (the form of good ol’ vitamin C most commonly found in skincare products) is often cited as a must-use ingredient, especially in the summer. Why is that?

“Ascorbic acid is a potent antioxidant and has been shown to reduce some of the damaging effects caused by UV exposure,” explains Ko. But “it is not a replacement for proper sun protection, like clothing, shade or sunscreen. Think of it as a supplement!”

So, what about the aforementioned paper that claims that topical glycolic acid has some photoprotective effects?

“This experiment is one of the only ones that has found a photoprotective effect from glycolic acid,” says Ko. “And if we look at the paper itself, we find that there isn’t much to it. There’s a description of the product applied in terms of the glycolic acid and pH, but we don’t know if other ingredients were included in the cream. It’s possible there were other antioxidants in the formula that could have contributed to the [photoprotective] effect.” There’s also “no statistical analysis, no data presented, no breakdown of the subjects by age or phototype—all things which are relevant and help us interpret scientific experiments.”

It’s also worth noting that the results of the study found that the glycolic acid resulted in a photoprotective effect to skin, but only in the form of SPF 2.4. (That’s two point four.) Need we say more?

Ko explains that other “more complete” experiments, such as this one, have found the opposite effect: “an increase in sun sensitivity when skin is treated with glycolic acid and then exposed to UVB.”

What about BHAs like salicylic acid?

Interestingly, this study shows that salicylic acid is seen to produce no significant changes when it comes to skin sensitivity to SSR (solar simulated radiation), DNA damage and sunburn cell formation. “Salicylic acid is a UVB absorber, which may explain some of the reduction in UV-induced damage in this experiment,” says Ko. In fact, “salicylic acid has structural similarities to some [compounds used in] sunscreens, like homomenthyl salicylate (homosalate), ethylhexyl salicylate (octyl salicylate) and trolamine salicylate.” So while salicylic acid may not make your skin as sensitive to sun damage as AHAs like glycolic acid, it is still “not a sunscreen and should not be treated or used as one,” says Ko.

The main takeaway? You guessed it: Just wear sunscreen. Every single day.

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