What are Alpha Hydroxy Acids?

alpha hydroxy acids in a dropper

Alpha hydroxy acids (AHAs) are a group of commonly-used acids. This set of acids are used across skincare products. However, alpha hydroxy acids also have quite the intimidating name, and unless you’ve done research on your own, you may not know what these acids are or what they do. Today we’re going to unveil the origins and benefits of alpha hydroxy acids for you.

woman holding dropper with AHA serum

What are AHAs and where do they come from? 

Alpha hydroxy acids are chemical exfoliators that can be either plant-based or derived from animal products. Scientifically speaking, they are a carboxylic acid substituted with a hydroxyl group. If that went right over your head, don’t worry.

AHAs are water soluble, meaning they dissolve in water-based formulations, and work primarily on the surface of your skin, though can penetrate deeper into the epidermis. This is different from a surface exofliant like a sugar scrub that can really only work on the outer layer of skin. And unlike a harsh scrub, AHAs exfoliate the skin without causing microabrasions.

Despite having a scientific name, there are numerous natural sources of AHAs (though they can also be made synthetically in labs). These include the most common AHAs, lactic acid and glycolic acid. Other natural forms of AHA include citric acid, mandelic acid, malic acid, and tartaric acid.

Contrary to common belief, lactic acid is not the same as lactose, a sugar found in dairy that many people have sensitivity to. Instead, lactic acid is a natural byproduct of fermentation, or the controlled aging of food (including fruit and vegetables). That’s right, lactic acid is almost always vegan friendly!

Some of your favorite foods, like sourdough, kimchi, or pickles contain lactic acid. And commercially, lactic acid is produced by fermenting sugars and starches (aka our friends carbohydrates), though can sometimes be derived from fermenting dairy, though this is far from the most cost-effective way of producing it.

Similarly, glycolic acid comes from cane sugar and some fruit. Of all commercial AHAs, glycolic acid has the simplest struct and the lowest molecular weight, making it easier for your skin to absorb topically. Of all the AHAs, glycolic and lactic acid have had the most research conducted on them and are seen as the most effective.

different types of products in bottles that are formulated with alpha hydroxy acids AHAs

Benefits and uses of alpha hydroxy acids 

Alpha hydroxy acids can be found in toners, cleansers, moisturizers, masks, scrubs, peels and AHA serums. Though first and foremost, all AHAs are exfoliants. It sounds scary, but the acids work to loosen and scrub away dead skin cells and other things on your skin like dirt.

As dead skin cells are removed from your skin and face, this creates room for newer, fresh-looking skin cells to shine through. This then makes skin look fresher and more glowing because the dull skin cells are gone and newer ones emerge to repair and replace what the AHAs have removed.

AHAs are also often associated with anti-aging benefits like fighting fine lines and even acne. These liquid exfoliants help kickstart the production of new collagen, making skin firmer and less saggy. The accumulation of dead skin cells can also amplify the appearance of wrinkles, so cleansing them away also helps in that sense. Like most cleansing productions, they can also help clear out blackhead-causing blocked pores.

One of the best things about AHAs is that the process of sloughing off skin cells begins to happen as soon as the product is applied. If the AHA is at a strong enough concentration, you should experience noticeably smooth skin that is brighter and softer in a matter of days.

a lemon and a bottle of citric acid as another type of AHAs

Is there anything else you need to know about alpha hydroxy acids? Yes—there can be downsides to using them.

The key measure for acids used in exfoliation (and also, for most skin treatments) is dosage of the ingredient. Full-strength AHAs are not appropriate for every day use, as they could cause severe irritation to the skin. However, ultra-low doses can be used on a daily basis.

The difference is that the high dosage acid treatment should be applied by a licensed skin care professional, and one can expect to see irritation as a side effect for a few days before the glow effect begins to be seen. With daily, low dosage, there is no irritation but it could take 10-12 days before the glowy effect begins to be seen. In either case, remember to use SPF when going out, as the new, sensitive skin is more prone to UV damage.

It can also be possible that the acid pH is not right for your skin. When applying an AHA, you should feel a light tingling. Anything stronger that feels more like a burning sensation means that either the percent concentration is too high, or the pH is off.

The ideal pH is between three and four (the approximate acidity of orange juice). Unfortunately, the pH of the acid is hardly ever included on the label.

According the the FDA, there is also significant evidence to show that AHAs increase (temporary) sensitivity to UV light and sun damage, though why this occurs is not clear. For this reason, we recommend using AHA products at night and being very aware of your sunscreen usage during the day (though of course, you should be applying SPF every day). You wouldn’t want to undo the hard work you’ve put into improve your complexion!

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