What Do Different Face Acids Do?

What You Need to Know About the 6 Main Skincare Acids

Mar 31 2018 by Wendy Gould

If you've ever felt overwhelmed by the skincare world, know that you're not alone. There's a veritable alphabet soup of vitamins, a constant debate over silicones, preservatives, and alcohols, and a never-ending stream of words like "occlusives," "parabens," and "surfactants."

Though it's impossible to cover everything in a day (let alone a single article), we can start somewhere. And today, that somewhere is acids. With the help of board certified dermatologists, we're breaking down six different types of acids by explaining what they are and how they can benefit your skin.

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Glycolic Acid

Glycolic acid is an alpha hydroxy acid (AHA) that’s derived from common, sugar-laden fruits, including pineapple, papaya, and unripened grapes. It’s a popular acid in skincare because it’s water soluble and also the smallest of all the AHAs, which means it easily sinks into skin to impart its goodness.

“It works by penetrating the top level of the skin and breaking down damaged surface cells,” explained Dr. Mark Gray, a Harvard-trained pathologist and dermatologist and the founder of Ao Skincare. “It is essentially an exfoliant, and can be superficial or deep depending on the concentration or strength.”

Over the counter products contain mild concentrations of glycolic acid, but if you want a heavy-duty exfoliation via GA, then you’ll want to head to a professional clinic or spa.

“Frequent use of the appropriate formulation can lead to significant improvement of acne, as well as a reduction in fine lines and irregular texture of sun-damaged and aged skin,” added Dr. Brian Zelickson, a dermatologist and the founder of MD Complete.

He added that when using glycolic acid, it’s super important to lather on sunscreen, as it can make your skin more sensitive to UV rays.

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Salicylic Acid

“Salicylic acid is considered the only BHA used in topical products,” said Dr. David Lortscher, a dermatologist and the founder and CEO of Curology. “It promotes an exfoliation, or shedding, of superficial skin cells, which provides a smoother texture and appearance to the skin.”

By actively sloughing off dead skin cells, salicylic acid prevents and treats blocked pores, and it can even give the illusion of decreased pore size.

Salicylic acid is almost always made synthetically, but it was first extracted from willow bark. You can find it in many over-the-counter products, ranging from cleansers to creams to wipes to spot treatments. It’s particularly ideal for oily and acne-prone skin types, and we recommend using it sparingly. High concentrations (at or over 2 percent) should be relegated to spot-treatment only. Milder concentrations can be used as a cleanser or cream.

Dr. Lortscher added, “BHAs do not cause photosensitivity, so they can be used morning or night, although the FDA still advises sun protection if you use a BHA product.”

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Lactic Acid

Lactic acid is also an AHA, and you might have guessed from the name that it’s often found in milk. Sour milk, that is, including yogurt, kefir, and cottage cheese. Interestingly, it’s also found in fresh, organic honey.

“Lactic acid is a popular ingredient in anti-ageing and rejuvenating skin care products, as it is a relatively mild and gentle on the skin,” said Dr. Gray. It’s also a wonderful ingredient to calm acne-prone skin.

You can purchase mild concentrations over the counter or schedule an appointment with a professional for a more potent facial. For daily use, we recommend about a 10 percent concentration. If you have really irritated, peeling, or highly sensitive skin, consult your dermatologist before using.

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Kojic Acid

“Kojic acid is found in many species of fungi — particularly the Japanese Aspergillus oryzae (Koji),” said Dr. Zelickson. “It is also created as the by-product of fermenting rice to make sake.”

Kojic acid is a mighty antioxidant that works by inhibiting pigment formation in plant and animal tissue. For example, it’s used to prevent brown spots on fruit and seafood, and has a similar effect in skincare.

“Similar to vitamin C, it decreases an enzyme called tyrosinase, which is important in melanin formation. For these reasons, it is abundant in skin products and peelings agents designed to brighten irregular or uneven pigment,” explained Dr. Zelickson. “This is a great ingredient choice for women who are concerned about pigment, but are pregnant or breast-feeding.”

As with many active products, it can cause skin irritation and potential allergic reactions in sensitive individuals. We recommend doing a test strip behind your ear or back of the neck and waiting a few days before moving forward with a product.

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Azelaic Acid

Azelaic acid isn’t talked about very much in the greater skincare community, but that doesn’t mean it should be pushed under the bathroom rug. In fact, if we had our way it’d be the shiny centrepiece on any vanity!

This lesser-known acid is derived from grains, including wheat, barley, and rye, and is often used in skin care products to treat acne, acne rosacea, and hyper-pigmentation, said Dr. Zelickson.

Here's why we love it: azelaic acid is naturally keratolytic, which means it actively eats away at excess skin growth. It's also antioxidant rich, anti-bacterial, anti-inflammatory, and contains the aforementioned tyrosinase enzyme, which reduces hyperpigmentation to give you a more even, glowing complexion.

Image Source: UnSplash / Daniel Hansen

Mandelic Acid

Mandelic acid is derived from bitter almonds and, though not super popular, is heralded as an anti-ageing, skin-clearing superhero by those who are in-the-know.

In terms of anti-ageing, it prevents and reduces existing fine lines by speeding up cell turnover, boosting collagen production, lightening hyperpigmentation, and firming the skin. It also sloughs off dead cells, which further minimises the appearance of fine lines.

This sloughing action, paired with its ability to press the “chill out” button on sebum production — also makes it a wonderful ingredient for those with acne-prone skin. As mentioned before when discussing salicylic acid, it removes dead cells prevent and treats blocked pores.

Image Source: UnSplash / Juan José Valencia Antía