PHAs, or polyhydroxy acids, are a gentler relative of glycolic and lactic acid. Gluconolactone and lactobionic acid are the common ones on labels. They smooth rough, dull skin like other exfoliating acids but with less stinging, and they also help skin hold water. A 12-week comparison found results close to glycolic acid.
- Helps with
- rough texture, dullness, sensitive skin that stings with acids, fine lines
- Evidence
- Limited. A few clinical studies, largely from the ingredient's developers; the head-to-head comparison with glycolic acid is the key one.
- Typical strength
- Not stated in the study summaries cited here; products list gluconolactone or lactobionic acid by name
- Works well with
- moisturizer, daily sunscreen, retinoids (tested in combination)
- Be careful with
- other exfoliating acids on the same night
What do PHAs do for skin?
PHAs are for people whose skin wants exfoliating but hates it: rough, dull patches that need smoothing, on a face that stings and turns pink with glycolic acid. They loosen the worn surface layer more slowly, so skin smooths out with less of the prickly feeling.
A 2004 review puts it directly: PHAs “provide similar effects as AHAs but do not cause the sensory irritation responses that can limit the use of classical AHAs.” The same review describes them as suitable for clinically sensitive skin, able to help skin hold water, and notes that most PHAs also act as antioxidants.
Are PHAs as effective as glycolic acid?
Close, in one 12-week study. People used either a gluconolactone (PHA) regimen or a glycolic acid (AHA) regimen. Both improved lines in silicone casts of the crow’s-feet area, overall photoageing grades and skin bounce. Glycolic acid did a little better on two measures at 12 weeks: sallowness improved 17.1% versus 12.4%, and skin bounce-back 13.5% versus 10.2%. Stinging and burning were significantly worse with glycolic acid at both 6 and 12 weeks. For the stronger relatives, see glycolic acid and lactic acid.
Can you use PHAs with retinoids?
The developers tested several combinations: PHA products alongside a prescription retinoid for adult breakouts were well tolerated, and PHAs with a vitamin A ester smoothed and plumped skin. That supports gentle pairing, but bring in one new product at a time; see skin cycling.
How long until you notice a difference?
In the comparison study, skin was graded at 6 and 12 weeks, with clear improvement by 12 weeks.
How do you use PHAs?
In a toner, serum or cream in the evening, after cleansing and before moisturizer, with sunscreen every morning. PHAs belong to the same hydroxy acid family as salicylic acid, so use one exfoliating acid at a time.
Who should be careful with PHAs?
They were developed as a gentler alternative to AHAs, and the 2004 review reports PHA products as compatible with African American, Caucasian, and Hispanic/Asian skin in its studies. Patch test first if you react easily.
- Grimes PE, et al. The use of polyhydroxy acids (PHAs) in photoaged skin. Cutis. 2004;73(2 Suppl):3-13.
- Edison BL, et al. A polyhydroxy acid skin care regimen provides antiaging effects comparable to an alpha-hydroxyacid regimen. Cutis. 2004;73(2 Suppl):14-7.
- Kornhauser A, Coelho SG, Hearing VJ. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clin Cosmet Investig Dermatol. 2010;3:135-42.
Editorial content, not medical advice.