What Is PHA? An Ultimate Guide


If you are a skincare trend follower, polyhydroxy acids (PHAs) are the next thing to make ripples in the skincare realm. Whether you get your skincare knowledge from social media, friends, or your dermatologist, you can expect to hear more about PHAs in the future. 

“If you aren’t yet familiar with PHAs, now is the time! PHAs can be a useful addition to your skincare lineup.”

  • Shani Darden, Celebrity Esthetician

If you are a skincare aficionado, AHAs and BHAs are probably familiar acronyms. However, if you are new to skincare, you are probably wondering what all of these letters stand for. The acronyms AHA and BHA are for alpha hydroxy acids and beta hydroxy acids, respectively. 

It seems like everyone is jumping on the acid-based skincare train. With good reason! While hearing the word acid sounds a little scary, these wonder products can make your skin look amazing. They exfoliate, help clear up blemishes, and make your skin feel smooth by supporting proper cell turnover.

Cell turnover helps ensure that dead skin cells don’t remain on the top layer of the skin. This can cause our skin to look dull, and those dead skin cells can clog our pores which ultimately can cause blemishes. As our cells turn over, new and youthful skin cells are brought to the surface. 

If you have read about acid-based skincare but found that your skin was too sensitive to handle the ingredients, then there is news to share that you will be interested in. PHAs are the newest acid on the rise, and you don’t have to feel left out of the acid trend.

What Should I Know About AHA and BHA?

Before getting into PHAs, a quick crash course in AHA and BHAs is necessary. AHAs and BHAs are similar as they are types of chemical exfoliants, the difference in each is their molecular structure as well as the skin concerns that they help solve. Both acids take some time to see results, but with consistency, your skin will look clear and glowing.

AHAs are primarily used for mild hyperpigmentation like scars or age spots. They can also be used to address fine lines, wrinkles, and uneven skin tone. AHAs are water-soluble and exfoliate the surface of the skin. Since they are not oil soluble, they cannot get through the skin’s natural oils, and their effects are most noticeable on the top surface of the skin.

There are multiple types of AHAs, with some of the most popular types being glycolic acid and lactic acid. AHAs do take time for the skin to get used to, so it is best to start off with a lower concentration and allow a day or two between applications. 

BHAs are oil-soluble, and for that reason, they are able to penetrate deeper into the skin’s surface. Oily and blemish-prone skin benefits greatly from BHAs since the molecules can enter the oil-producing pores and clean out the excess sebum that builds up. 

The most common type of BHA is salicylic acid, which you’ll likely recognize if you have ever used any products to address acne. Salicylic acid is typically more widely tolerated, with many using it daily from the get-go. You can also find products that pack a punch with salicylic acid, and these are especially beneficial when you have a blemish pop up on a big day. I recommend Dr. Dennis Gross’ Alpha Beta Universal Daily Peel Pads to tone, smooth and help shed dead skin cells. 

For those with sensitive skin, AHAs and BHAs may be too harsh on the skin. You may have experienced this yourself if you had a bad reaction to either type of acid. Your skin's barrier may be compromised from using a highly concentrated acid, which can bring on a myriad of issues like flaky skin, irritation, and blemishes. This can be a frustrating feeling as you may now have more skin issues than you did in the beginning. 

Don’t swear off all acids, though, if you have had a previous bad experience with AHAs and/or BHAs. PHAs are the perfect stepping stone to get back into incorporating acids into your skincare routine and not have to worry about sensitivity issues. 

What Is PHA?

PHA products are related to AHAs and provide the same fantastic benefits but without the same irritation that can occur when using AHAs. Users who may see positive results using PHAs include those with certain skin conditions and those recovering from cosmetic procedures. PHAs are generally well tolerated by everyone. 

While we only did a crash course on AHAs and BHAs, we will go into a little more detail about PHAs since they can be used by every skin type and combined with other products quite easily. 

How Are PHAs Beneficial?

If you are wondering how PHAs and AHAs are related, it all comes down to their molecular structure. Their structures are both similar, but PHAs have a larger structure, and, as a result, the molecules penetrate the skin more slowly. This slow penetration also helps to hydrate your skin more than a typical AHA can.

PHAs act as humectants on the skin, attracting water. 

Along with their hydrating properties, PHAs are beneficial in that they exfoliate your skin, making it appear more smooth and radiant. Since your skin will be super moisturized, you’ll appear as if you are aging in reverse. 

What Are Common PHAs?

Just like AHAs and BHAs, there are multiple types of PHAs. The main three PHAs are gluconolactone, galactose, and lactobionic acid.


Like every other acid, gluconolactone chemically exfoliates dead skin cells from the epidermis, giving us smoother and brighter skin. It is also very moisturizing as it attracts water into the skin’s upper layer. 

While AHAs are water soluble, they do not attract water and do not have the same moisturizing benefit. 

While some AHAs have smaller molecules that can penetrate the skin, gluconolactone has larger molecules, meaning it cannot penetrate as deeply. This makes it more tolerable for those with sensitive skin. 

You can find gluconolactone in my Lactic Acid Serum which is specially formulated to help brighten your complexion and give it a natural-looking glow.


Galactose is a sugar found in milk, but it is also a PHA that can be applied to the skin. 

When galactose is used as a PHA, it can help reduce the appearance of fine lines and wrinkles, and just like gluconolactone, it is hydrating and can help the skin retain more moisture. You may notice fine lines appear when your skin is dry, but constant moisturization and the use of humectant products will plump up the skin with moisture and rid your complexion of fine lines. 

Galactose is gentle enough for all skin types and also gives a boost to other products by increasing their effectiveness. 

Lactobionic Acid

While lactobionic acid sounds a lot like its cousin lactic acid, and in fact, they both are derived from milk. Lactobionic acid may also be referred to as bionic acid to help differentiate it from its lactic-named cousin. 

Like the other PHAs, lactobionic acid molecules are larger and do not penetrate the skin as deeply. It remains on the surface of the skin and will help diminish the appearance of fine lines, wrinkles, and hyperpigmentation. 

If you have dry skin that is also sensitive, lactobionic acid is a great choice. This exfoliator is gentle enough for daily use and also contains antioxidants that protect your skin from free radicals. A great line of defense since your skin is the first barrier to the outside world. 

What Precautions Should I Take When Using Skincare Acids?

While PHAs are super mild and are commonly paired with AHAs and BHAs in a product, don’t try to combine separate PHAs, AHAs, and BHAs, as you may run the risk of irritation by doing so.

The same reasoning goes for combining PHAs with other active ingredients. Although PHAs are gentle and more tolerable, make sure your skin can handle this active ingredient on its own before trying to add other active ingredients to your routine. A good practice would be to only use one active ingredient at a time. 

If you do have sensitive skin, patch testing is a friend. Before using a new skincare product, test the product on a small part of your skin, like your forearm. Wait 24 hours to see how your skin reacts to the product. If your skin feels fine, then you know you can slowly incorporate it into your skincare routine. 

You’ll want to wear a broad-spectrum sunscreen when using any type of acid, PHAs included. Since these acids buff away dead skin cells and bring younger skin cells to the surface, your skin is thinner and more susceptible to sun damage. Combine your moisturizer and sunscreen for a double dose of protection in one product.

While we love anything that gives us instant gratification, skincare is one of those things where patience is a virtue. It takes time for products to make an impact on the skin, and consistency is key when using acids. 


Acid-based skin care products are becoming more and more popular and with good reason. The benefits of AHAs and BHAs are hard to beat, except when you have sensitive skin. Since sensitive skin is a common concern, it is great to have a skincare option so that everyone can enjoy the benefits of glowing skin.

Acids are only one part of your skincare routine. Cleaners, serums, toners, and masks all have a place on your vanity. 


The use of polyhydroxy acids (PHAs) in photoaged skin | National Library of Medicine

Hydroxy acids in skin care products | AccessScience from McGraw-Hill Education

Antiaging Effects of Topical Lactobionic Acid: Results of A Controlled Usage Study | MDedge Dermatology

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