What Is A PHA In Skincare & How To Use

If you've been curious about chemical exfoliants but found AHAs too irritating or BHAs too targeted, PHAs are worth trying. They've been around since the 1990s but are still relatively newer players compared to glycolic acid, which means the research body is smaller, but what's there is promising.

Known for their mild exfoliating properties, PHAs help lift away dead skin cells while supporting a smoother, more balanced-looking complexion, making them a popular choice for people with sensitive or easily stressed skin.

So, what is PHA? This guide covers what PHAs are, what the science says, and how to work them into a routine without overthinking it.

 

Key Takeaways:

• What PHAs Are: PHAs are chemical exfoliants that also hydrate, a combination that makes them one of the more skin-friendly options in the acids category, particularly for sensitive, dry, or reactive skin types.
• What The Science Says: The research is newer than glycolic acid, but it's pretty interesting. Gluconolactone, the better-studied PHA, has data supporting exfoliation, hydration, and even some photoprotection in vitro.
• How PHAs Interact With Other Products: PHAs generally play well with other actives. They're one of the more compatible exfoliants for layering with ingredients like retinoids and azelaic acid.

 

What Is PHA In Skincare?

PHA stands for polyhydroxy acid. In skincare, the two main PHAs you'll encounter are gluconolactone and lactobionic acid. Gluconolactone is significantly better studied of the two and will be the main focus here. If you spot lactobionic acid in a formula, the main thing to know is that it functions as a humectant (a water-attracting hydrator) in addition to its exfoliating properties.

 

How PHAs Compare To AHAs

Like AHAs, PHAs are chemical exfoliants that help speed up cell turnover and remove dead skin cells from the surface. The key structural difference is size: PHA molecules are larger than AHAs like glycolic acid, which means they penetrate more gradually. That slower movement through the skin is largely why PHAs tend to cause less irritation. Long story short, they're doing a similar job, just with less intensity.

 

The Hydration Bonus

One thing that makes PHAs interesting from a formulation standpoint is that they also attract moisture to the skin. Exfoliation and hydration in a single ingredient is a useful combination, especially for skin types that tend to feel drier or more reactive after acid use.

 

 

What The PHA Gluconolactone Does

Gluconolactone has a few different tricks up its sleeve, and the research, while still growing, covers more ground than you might expect. Here's what the data shows. 

 

Exfoliation, Even At Low Concentrations

One of the more useful findings in PHA research is that gluconolactone can deliver meaningful exfoliation at surprisingly low concentrations. A clinical study found that gluconolactone at 2% in both cleanser and leave-on formats significantly increased skin cell turnover rate compared to untreated skin, with consumer-reported improvements in texture, dullness, and overall skin feel (Edison et al., 2021). That's notable because most exfoliant research has focused on higher concentrations (8–10%+). For people who want exfoliation benefits without loading up on high-percentage acids, this is relevant.

 

Acne-Prone Skin Compatibility

One of the more compelling studies in PHA research is a double-blind trial on 150 patients comparing 14% gluconolactone to 5% benzoyl peroxide for mild-to-moderate acne. As a result of the experiment, both reduced the number of inflamed and non-inflamed lesions. The difference was that gluconolactone was observed to have fewer side effects, namely less irritation and dryness, than benzoyl peroxide (Hunt & Barnetson, 1992). That's a useful finding for anyone managing acne who has struggled with the dryness that comes with standard treatments.

 

Photoprotection In Vitro

This one is more of a "keep an eye on it" finding than a clinical guarantee, but it's interesting. In vitro research found that gluconolactone provided up to 50% protection against UV radiation-induced elastin promoter activation and didn’t significantly increase sunburn cell formation in human skin (Bernstein et al., 2004). This isn't a reason to skip sunscreen, though it is worth noting that increased photosensitivity is one of the reasons some people shy away from glycolic acid altogether. It does also suggest there may be some other mechanisms at play in this molecule beyond simple exfoliation.

 

PHA Skincare: Who Should Consider It?

The short answer is that most people can work PHAs into a routine in some capacity. But here's where they tend to make the most sense. 

• Sensitive Or Reactive Skin: This is probably where PHAs make the most obvious case for themselves. If AHAs like glycolic acid have been too harsh in the past, gluconolactone offers a gentler on-ramp to chemical exfoliation without completely sacrificing efficacy.
• Dry Or Dehydrated Skin: The combination of exfoliation and humectant properties makes PHAs practical for skin types that tend to feel tight or uncomfortable after acid use.
• Acne-Prone Skin: The comparative data against benzoyl peroxide is a legitimately useful context. PHAs aren't a replacement for prescription acne treatments, but for mild congestion and texture in people who find BPO too drying, they're worth considering.
• First-Time Exfoliant Users: PHAs are a reasonable starting point for chemical exfoliation beginners. Its lower irritation potential, hydrating properties, and compatibility with other actives make the learning curve more forgiving.
• More Established Routines: PHAs also have a role as a supporting player alongside more aggressive actives, where their gentle exfoliation and hydration complement ingredients such as retinol, adapalene, high levels of BPO, combination routines, etc. that are doing heavier lifting.

 

 

How To Add PHA To Your Routine

Most PHA products on the market are water-based toners and serums. Application is typically straightforward: apply to clean skin after cleansing, before heavier products like moisturizers.

• Starting Out: Once or twice a week in the evening is a reasonable beginning, especially if your skin is new to chemical exfoliation. From there, frequency can increase based on how your skin responds.
• Concentration: Exfoliation benefits show up at concentrations as low as 2% (Edison et al., 2021), so don't assume a low number means nothing is happening. As a rough guide: formulas around 5% and under sit in gentle daily maintenance territory; 10% and up deliver punchier exfoliation while still being well-tolerated for regular use; and anything at 30% and above is best thought of as a home peel. Our PHA exfoliant sits in that last category, a wash-off treatment that, used once a week, has shown little to no irritation and increased hydration over time in research on this ingredient.
• Sun Protection: While gluconolactone doesn't increase sun sensitivity the way AHAs do, sunscreen should still be a core part of any result-driven routine, PHA or otherwise.

 

Can You Use PHA With Other Actives?

This is one of the better parts of the PHA story. Thankfully, they tend to play well with others!

 

Can You Use PHA With Retinol?

PHAs are a solid companion to retinoids because their gentler exfoliating action and hydrating properties can help offset some of the dryness or irritation that comes with retinol adjustment. Many people alternate evenings, with PHA one night and retinol treatment the next, especially when first introducing a retinoid. If your skin handles both well, using them in the same routine isn't necessarily off-limits, but going slow and watching how your skin responds is the sensible approach.

 

Can You Use PHA Every Day?

For most people, yes, particularly at lower concentrations. Because gluconolactone is gentler than classic AHAs, daily use is more accessible than it would be with something like glycolic acid at a comparable concentration. Sensitive skin types should still start slowly and build frequency, but daily use is a realistic endpoint for many people.

 

Can You Use PHA And BHA Together?

This is technically possible, but this combination warrants caution depending on the specific products and your skin's tolerance. BHA (salicylic acid) is oil-soluble and works deeper in the pore, while PHA works more at the surface. So, they're addressing somewhat different things. If you're going to combine them, occasional rather than daily use is a more conservative starting point, and paying close attention to how your skin responds is the right move.

 

Can You Use PHA And AHA Together?

PHAs and AHAs can be combined, and they're actually often formulated together. A PHA treatment that pairs gluconolactone with a gentler AHA, like lactic acid, is a common formulation strategy. As with any combination of exfoliants, the rule is to introduce gradually and not overdo frequency, especially at the start.

 

 

Final Thoughts

PHAs don't have the decades of research behind them that glycolic acid does, and they're not going to replace more established actives for concerns like photoaging or stubborn hyperpigmentation. What they do offer is a well-tolerated, multitasking exfoliant option that hydrates while it clears away dead cells, works at surprisingly low concentrations, and earns its place in both beginner and more complex routines. For anyone who's been intimidated by acids or frustrated by irritation, it's an ingredient category worth looking into.

 

Frequently Asked Questions About What PHA Is

Is PHA a natural ingredient?

PHAs can be derived from natural sugar sources, but the versions used in skincare are refined for cosmetic formulations, similar to most cosmetic actives.

 

Does PHA need to be rinsed off?

It depends on the format. Most PHA serums and toners are leave-on products, but cleansers containing PHA are rinsed off. High-concentration wash-off peels are also a format that’s typically left on for a short time, then rinsed.

 

Can PHA be used on the neck?

Yes, though it's worth keeping in mind that neck skin tends to be more prone to irritation than facial skin. Sticking to lower concentration products is a good rule of thumb for that area.

 

Does PHA have a strong smell?

Most PHA skincare products have little to no noticeable scent unless fragrance has been added.

 

Should PHA be stored in a special way?

 Gluconolactone is generally speaking a pretty stable ingredient! You don’ tneed to worry about degradation as much as your retinoids or your vitamin Cs. That said, like any product, store in a  cool dark place and you should be good to go.

 

Is a higher PHA percentage always better?

Not necessarily. Research shows meaningful exfoliation at concentrations as low as 2%. The right concentration depends on your skin's tolerance and what you're trying to address.

 

References:

1. Hunt, M.J. and Barnetson, R.S. (1992), A COMPARATIVE STUDY OF GLUCONOLACTONE VERSUS BENZOYL PEROXIDE IN THE TREATMENT OF ACNE. Australasian Journal of Dermatology, 33: 131-134. https://doi.org/10.1111/j.1440-0960.1992.tb00100.x
2. KSENZENKO, S., KAIDBEY, K., SCHWARTZ, M., BROWN, D., & BERNSTEIN, E. (2004). The Polyhydroxy Acid Gluconolactone Protects Against Ultraviolet Radiation in an In Vitro Model of Cutaneous Photoaging. Dermatologic Surgery, 30(2), 189–195.
3. Edison B, Smith H, Green B ... 27887 Skin exfoliation with low concentrations of alpha hydroxy acids and poly hydroxy acids when incorporated into wash-off or leave-on products using a novel abbreviated model to measure cell turnover rate Journal of the American Academy of Dermatology, 85AB165