Ingredient Comparison
PHA vs AHA
PHAs, such as gluconolactone, and the related lactobionic acid are close relatives of AHAs like glycolic and lactic acid. Both loosen dead surface cells. In a 12-week comparison, a PHA routine gave broadly similar anti-aging results with less stinging, though AHAs did a little better on two measures and the research base for PHAs is much smaller.
Choose a PHA if your skin is sensitive, dry or new to acids, or if AHAs have made it sting. Choose an AHA if your skin tolerates acids and you want the most studied option for dullness, rough texture and sun-related changes. Both work gradually, and neither replaces daily sunscreen or a retinoid for deeper signs of aging.
- PHAs exfoliate like AHAs but caused less stinging and burning in a head-to-head trial.
- AHAs have far more research and did slightly better on two anti-aging measures in that trial.
- AHAs clearly raise sun sensitivity; one PHA did not increase sunburn cells, but daily sunscreen is wise with either.
At a glance
How PHAs and AHAs differ
Both are hydroxy acids that exfoliate the skin surface. The practical differences are comfort, hydration, sun sensitivity and how much research stands behind each.
| Factor | PHA (polyhydroxy acids) | AHA (alpha hydroxy acids) |
|---|---|---|
| Examples | Gluconolactone; lactobionic acid is a close relative. | Glycolic, lactic and mandelic acid. |
| Molecule | Larger, with several water-attracting groups. | Smaller; glycolic acid is the smallest. |
| Stinging and burning | Less, in a 12-week comparison. | More, especially at higher strengths and lower pH. |
| Hydration | Described as humectant; gluconolactone raised skin moisture in a small study. | Exfoliation is the main effect. |
| Anti-aging results | Broadly similar to an AHA routine at 12 weeks. | Slightly better on sallowness and skin elasticity in the same trial. |
| Sun sensitivity | Gluconolactone did not significantly increase sunburn cells in one study. | Shown to raise UV sensitivity; it fades about a week after stopping. |
| Research depth | Limited, and much of it industry funded. | Extensive. |
| Best fit | Sensitive, dry or acid-new skin. | Normal to oily skin that tolerates acids. |
Evidence profile
How confident is this comparison?
Confidence is shown in plain categories, not a numerical score.
There is one direct comparison of PHA and AHA routines, plus small studies of PHAs alone. The direct comparison and the main review were supported by a company that sells PHA products.
In a 12-week trial, both routines improved signs of photoaging. The AHA routine did slightly better on sallowness and skin elasticity, while stinging and burning were significantly worse with the AHA.
In a split-face study of 16 women, gluconolactone treatments significantly raised skin hydration, with no difference between 10% and 30% strengths.
FDA reports that after four weeks of AHA use, sensitivity to UV redness rose by 18% and UV cell damage doubled, returning to normal a week after stopping.
A review says PHAs are compatible with sensitive skin, including rosacea and eczema, but the supporting studies are small and not independently replicated. Patch test and go slowly.
Choose by goal
Which one fits your situation?
Pick the acid your skin can use comfortably and consistently, not the one that sounds strongest.
Products often sting or burn
A PHA is the gentler first acid. See the sensitive skin routine.
Lean toward: PHA
Flaky, rough and tight
PHAs add hydration as they exfoliate. Lactic acid is a reasonable AHA option if your skin tolerates it.
Lean toward: PHA, or lactic acid
Normal to oily skin that tolerates acids
AHAs have the stronger track record. See glycolic acid.
Lean toward: AHA
Rosacea or eczema-prone skin
Get a diagnosis first. If your clinician agrees an acid is suitable, a PHA is the cautious choice. See rosacea.
Lean toward: PHA, with care
Prone to dark marks after irritation
Irritation can leave new marks, so the gentler acid is a sensible start. See skincare for darker skin tones.
Lean toward: PHA, start low
Pregnant or breastfeeding
AAD pregnancy guidance includes an evening glycolic acid product. PHAs are not specifically addressed, so confirm with your clinician.
Lean toward: Either, with clinician input
Strengths and limits
What each acid family does well, and where it falls short
PHA
Where it does well
- Less stinging and burning than an AHA routine
- Hydrating as well as exfoliating
- Did not raise sunburn cells in one study
- A comfortable first acid for many people
Where it falls short
- Much less research than AHAs
- Key studies supported by a company that sells PHAs
- Gentler effect may mean slower change
AHA
Where it does well
- The most studied exfoliating acids
- Long track record for texture and dullness
- Slightly better on two anti-aging measures in the comparison
Where it falls short
- More likely to sting or burn
- Shown to raise sun sensitivity
- Can leave dark marks on darker skin if it irritates
- Less suited to reactive skin
Moving from a PHA to an AHA
How to step up without irritation
Wait for stable tolerance
Use your PHA comfortably for several weeks, with no stinging or flaking, before changing anything.
Start low and less often
Choose a low-strength AHA, ideally lactic or mandelic acid, once or twice a week.
Replace, do not stack
The AHA takes the PHA’s place rather than becoming an extra acid layer.
Step back if needed
If redness, stinging or tightness appears, return to the PHA or use the AHA less often.
Using both and routine fit
Can you use them together, and what pairs well?
Using both
Some products blend PHAs and AHAs, which is fine. Layering two separate acid products adds irritation without a clear extra benefit, so most routines work better with one.
What pairs well
Hyaluronic acid, ceramides and a plain moisturizer pair well. Keep retinoids on separate nights, as the AAD warns combining exfoliation with retinoids can dry the skin.
Who funded the PHA research: the head-to-head PHA vs AHA trial and the main PHA review were published in a 2004 journal supplement supported by a company that sells PHA products. The findings are plausible and fit with later small studies, but they have not been widely repeated by independent groups. That is a reason for realistic expectations, not for avoiding PHAs.
Safety and professional-help boundaries
When this choice needs more than a product switch.
- Use broad-spectrum SPF 30 or higher daily while using any AHA and for a week after stopping, as FDA advises; it is sensible with PHAs too.
- Never exfoliate open cuts, wounds or sunburned skin.
- If every product stings or your skin looks shiny and tight, you may have over-exfoliated skin; pause all acids.
- Persistent burning, swelling or a rash is not an adjustment phase; stop and seek medical advice.
- Avoid strong chemical exfoliation if you have a darker skin tone or are prone to dark spots, as the AAD advises.
Frequently asked questions
Short answers to common questions
Is PHA better than AHA?
Not better, but gentler. In a 12-week comparison, a PHA routine gave broadly similar anti-aging results to an AHA routine with significantly less stinging and burning, while the AHA did slightly better on two measures.
Is PHA good for sensitive skin?
It is usually the best acid to try first. Studies describe PHAs as causing less irritation than AHAs, and a review reports they are compatible with sensitive skin, though that evidence is limited.
Does PHA make you sensitive to the sun?
One study found gluconolactone did not significantly increase sunburn cells in human skin, unlike AHAs, which are shown to raise UV sensitivity. Daily sunscreen is still a good idea with any exfoliant.
Can I use PHA and AHA together?
Some products blend them, which is fine. Layering separate acid products increases irritation risk, so most routines are better with one.
Is gluconolactone a PHA?
Yes. Gluconolactone is the most studied PHA, and lactobionic acid is a related ingredient often grouped with PHAs. Both are used in gentle exfoliating products.
Does PHA work as well as glycolic acid?
For general anti-aging signs, one 12-week trial found the two routines broadly comparable, with glycolic acid slightly ahead on sallowness and skin elasticity. Glycolic acid has much more research overall.
How often should I use a PHA?
Start once or twice a week and increase only if your skin stays comfortable. Stop or slow down if it stings.
Editorial Record
- Editorial status
- reviewed
- Medical reviewer
- Dr. Abdurrahman Efem
- Practical reviewer
- Merve Akkaya
- Last reviewed
- November 13, 2026
Related pages
Continue from here
Sources reviewed
Evidence behind this comparison
- Edison BL, Green BA, Wildnauer RH, Sigler ML. A polyhydroxy acid skin care regimen provides antiaging effects comparable to an alpha-hydroxyacid regimen. Cutis, 2004.
- Grimes PE, Green BA, Wildnauer RH, Edison BL. The use of polyhydroxy acids (PHAs) in photoaged skin. Cutis, 2004.
- Bernstein EF, Brown DB, Schwartz MD, et al. The polyhydroxy acid gluconolactone protects against ultraviolet radiation in an in vitro model of cutaneous photoaging. Dermatologic Surgery, 2004.
- Jarząbek-Perz S, Mucha P, Rotsztejn H. Corneometric evaluation of skin moisture after application of 10% and 30% gluconolactone. Skin Research and Technology, 2021.
- US Food and Drug Administration: Alpha hydroxy acids.
- American Academy of Dermatology: How to safely exfoliate at home.
- American Academy of Dermatology: Pregnancy skin care guidance.
Sources support the general editorial conclusions shown here. They do not replace personal medical advice from a qualified clinician, and they do not prove that every product containing these ingredients will perform the same way.