AHAs, BHAs...PHAs?! What's a PHA & How to Use

In our final podcast episode of 2021, we dedicated the meat of the episode on a chemical exfoliants update. That’s the alphabet clan of PHAs, AHAs, and BHA, and it resulted in a lot of curiosity about PHAs. Though PHA research is still relatively new and not as well-studied as classic glycolic acid, there’s still some really exciting data that validates it’s use as an exfoliator. In fact, we like gluconolactone so much we use 30% of it in our Baby Steps exfoliating treatment! So let’s do a deeper dive into the science, what to expect, and how to shop for this ingredient!

What is a PHA?

PHA stands for polyhydroxy acid, and in the skincare realm, the two main PHAs you can find are gluconolactone and lactobionic acid. Between the two molecules, gluconolactone is the much better understood molecule, and what we’ll mainly focus on in this blog post. If you spot lactobionic acid in your product, just know that it’s an incredibly effective humectant (water-loving hydrator).

Okay! So what does gluconolactone do for my skin?

PHA gluconolactone is a talented, multi-faceted molecule! Like AHAs such as glycolic, lactic acids, gluconolactone is a chemical exfoliant that helps to speed up cell turnover. It can help exfoliate even at as low as 2% use daily. However, higher levels of gluconolactone can deliver additional benefits.

One of the most notable studies compared 14% gluconolactone to 5% acne-fighting superstar benzoyl peroxide with a whopping 150 patients. This study found that gluconolactone was comparable to BPO, but with fewer unwanted side effects such as irritation and dryness.

In fact, PHAs are fantastic hydrators that are well tolerated by most skin types. One study looked at using 30% gluconolactone once a week as a peel and showed no irritation and increased hydration over time. There’s also a Neostrata study that looked at using 15% azelaic acid in conjunction with a 10% gluconolactone moisturizer in rosacea patients that further decreased erythema compared to azelaic acid alone.

To sum up, PHA gluconolactone has both hydration and acne-fighting benefits, making it a suitable chemical exfoliator for all skin types. Of course, the downside is that it’s not as well-established in combating photoaging, fine lines, and hyperpigmentation as the OG, glycolic acid. Ultimately, we would recommend this as a fantastic alternative for those easily sensitized by AHAs.

gluconolactone snapshot

Shopping for Gluconolactone

Even as the new kid on the block, there are quite a bit of products to go through! The two key things to look at are: gluconolactone concentration and its supporting cast. Gluconolactone is a well-tolerated ingredient that can be used as a leave-on product at as high as 15% and as a rinse-off peel at 30%. However, if you’re highly sensitive, you can still get exfoliation benefits even as low as 2%. Many gluconolactone products on the market come in combination with other actives, so it’s important to pay attention to the supporting cast. 

chemist's breakdown of the gluconolactone product landscape

    How do I add a PHA to my routine?

    Most gluconolactone products you see on the market are water-based toners and serums. We would use them daily at night as the first step post cleansing. It’s gentle enough that you can use it both during day and night (don’t forget to slap on that sunscreen!). If you’re new to chemical exfoliation and want to proceed with a lot of caution, you can start with a lower level product such as the Inkey List toner. Most people can jump right into a 7% to 10% with no issues.

    If you’re wondering whether or not you can pair PHAs with your existing actives, the answer is – yes! Compared to say the classic glycolic acid, gluconolactone is much better tolerated and can function as a great side kick to other guys such as azelaic acid or retinoids.


    • PHAs, gluconolactone and lactobionic acid, are relatively “newer” chemical exfoliants
    • They are great AHA alternatives for those with sensitive skin 
    • They pair well with aggressive active ingredients like higher concentrations of retinol
    • Gluconolactone is both hydrating and exfoliating even at lower levels (~2% conc.), but to really see results try to aim for at least 10%.

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    1 comment

    Can you use a pha and a retinol in the same routine? Meaning, use a pha toner followed by a retinol at night?

    Kasey Solomon February 02, 2022

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