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AHA, BHA, and PHA: The Exfoliating Acids You Need to Know About

Woman applying cosmetic acid to her face using a small cotton pad.

If you think a good scrub can help improve your skin’s appearance, wait until you try exfoliating acids—they’re a godsend! Although scary, they’re safe to use at home, just as long as you choose the right one for you out of the three available categories.

Unlike exfoliating acids, scrubs have a coarse texture that can be abrasive to the skin and cause micro-tears and increased sensitivity. Some cleansing brushes can have a similar effect. Although they do get rid of impurities and leave your skin feeling soft, they only act on the surface and provide temporary results. Acids, on the other hand, go further deep into your skin to tackle any issue at the root.

Let’s take a little dive into the world of these seemingly magical serums.

What Are Exfoliating Acids?

Exfoliating acids are skincare products that can help you achieve that sought-after glow by clearing off the dead cells that accumulate on the top layer of your skin. By breaking down the protein bonds that hold these old cells together and stuck to your face, they prevent them from clogging up your pores, which can cause breakouts, blackheads, and acne. 

Acids also have the power to increase collagen density and boost skin cell regeneration. This provides the skin with the elasticity it needs to reduce the appearance of fine lines and slow down the aging process we all dread. Furthermore, their low pH level helps inhibit the growth of harmful bacteria and regulate sebum (oil) production, preventing inflammation as well as a number of other skin concerns. 

The end result is clear, smooth, and rejuvenated skin, with improved texture and magnified brightness. It might sound too good to be true, but if you consider that these are the acids used by aestheticians for chemical peels, it makes it easier to believe in their effects. 

The Three Types of Exfoliating Acids

Various face serums laid out on a pink background with plant leaves.

Before you jump on the acid wagon and start creating your own little collection, you should get acquainted with the three acid families available on the market. 

  • Alpha Hydroxy Acids (AHAs): These are water-soluble acids that focus their action on problems found on the outermost layer of the skin, such as blemishes, sun damage, and hyperpigmentation. They help even out skin tone, improve minor breakouts, and accelerate skin cell regeneration. They’re also humectants, which means they provide extensive moisture to dry skin, giving it a younger and dewy look. AHAs include glycolic, lactic, and mandelic acids, and they’re ideal for people with sensitive skin.
  • Beta Hydroxy Acid (BHA): If you’re looking for some serious skincare action, opt for salicylic acid, the only member of the BHA family. This oil-soluble acid is able to penetrate deeper into your skin layers, dissolving all impurities to clear out spots and shrink pores, and reduce excess oil production. It has anti-inflammatory and antibacterial properties, which makes it ideal for problematic and stubborn skin conditions. Compared to AHAs, salicylic acid is more suited for oily skin affected by blackheads, acne, or rosacea. Those allergic to aspirin should not use this product. 
  • Polyhydroxy Acids (PHAs): People with reactive skin are the ones who can benefit from PHAs the most. They have similar effects to AHAs, but due to the larger size of their molecules, they take longer to penetrate the skin and do their job. They’re anti-inflammatory and contain antioxidants, which can strengthen the skin barrier function and minimize irritation. They’re suitable for skin affected by eczema and atopic rosacea due to their gentle exfoliating action and their humectant properties. PHAs include lactobionic and gluconolactone acids. 

Finally, A Word of Caution

We have two layers of caution to prepare you with. First, the mild caution. There’s no doubt that exfoliating acids are a skincare must if you want to keep your skin vibrant and happy. However, they’re still acids and as such, they should be used with caution. Numerous factors must be considered when choosing the right one for you, including your skin type, the concentration of the solution, the pH level, and the effects of any added fillers. While most product labels indicate what skin type they’re suited for, it’s always best to do a patch test first to see how you react to it, thus preventing possible full-face irritation. If unsure, consult with your dermatologist or aesthetician before you make a purchase. 

Finally, a much more serious caution: stick with familiar products from familiar companies. The chances of doing permanent damage to your body using acid exfoliants sold over the counter at your local Walgreens from companies like Proctor & Gamble are about as close to zero as you can get. The chances of seriously hurting yourself by ordering acids off eBay and rolling your own DIY dermatologist office at home? Well, those chances are much higher, and if you do any poking around online, you’ll see absolute horror stories where people tried to replicate spa/dermatologist treatments at home without understanding what they were getting into.

When it comes to at-home treatments, you want to use gentle products that work over the span of days to weeks, not harsh products that work so quickly you’ll be in trouble if you apply them incorrectly.

Carla Cometto Carla Cometto
Carla has been writing professionally for five years and blogging for many more. She's worked as a journalist, photographer, and translator. She's also an avid traveler who hopes to inspire a sense of curiosity and adventure in others through her writing. Read Full Bio »
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