What does PHA (Polyhydroxy Acid) do?#
PHAs (polyhydroxy acids) are a gentler class of exfoliating acids with larger molecules that work more gradually on the skin's surface. They provide exfoliation while simultaneously supporting hydration, making them an excellent choice for sensitive skin or those new to exfoliants.
- Helps promote smoother, more refined-looking skin with a gentle touch
- Supports skin hydration while exfoliating, unlike harsher AHAs
- Well-suited for sensitive skin and those new to chemical exfoliation
How it works
PHAs like gluconolactone and lactobionic acid gently smooth away dull surface buildup for smoother, brighter-looking skin. Their larger molecular size is linked to a more gradual, gentler action than AHAs, which contributes to their milder profile. Unlike most exfoliants, PHAs also act as humectants, helping the skin feel hydrated rather than stripped, so the skin looks smoother and more comfortable after use.
How to use PHA (Polyhydroxy Acid)#
- A leave-on step: after cleansing, before your moisturizer.
- Evening is the easier place for it, though it suits either time of day.
- Across the whole face rather than dabbed onto single spots, and keep it away from the eye area. Rinse with plenty of water if any gets in your eyes.
- Follow the frequency on the pack. It sits at the gentle end of the exfoliating acids, so there is no need to build up slowly.
- Wear sunscreen over the areas you have applied it before spending time in the sun.
- Follow it with a moisturizer. It draws water to the surface, so it sits comfortably alongside humectants and barrier creams.
- Mild tingling or dryness can turn up. Use it on fewer days rather than pushing through, and stop if it persists.
- Stick to one exfoliating product at a time — two acids in the same session is what usually causes the tightness.
- Keep it to a different evening from retinol.
- A good starting point for those who find AHAs or BHAs too intense.
Discontinue use if unexpected discomfort occurs.
The form you will see it in
PHA exfoliating serum
- Where it goes
- Before moisturizer
Using PHA (Polyhydroxy Acid) with other ingredients
Pairs well with PHA (Polyhydroxy Acid)
Hyaluronic Acid
Works well togetherTogether they help skin feel hydrated from multiple angles.
What not to use with PHA (Polyhydroxy Acid)
Eye-area retinol
Different timesThe eye area is thinner and takes longer to settle, so keep exfoliants to a different evening from your eye retinol.
Other exfoliants
Different timesMore than one exfoliant at once can feel drying, so they’re best kept to separate evenings.
Enzyme Exfoliants · Glycolic Acid (AHA) · Lactic Acid (AHA) · LHA · Salicylic Acid (BHA)
Retinoids
Different timesRetinoids and exfoliants can both feel drying, so they’re best kept to separate evenings.
Vitamin C
Different timesVitamin C and exfoliants are more comfortable at different times than layered in one routine.
Who should avoid PHA (Polyhydroxy Acid)?#
Six situations change whether PHA (Polyhydroxy Acid) suits your skin right now. Each one is either a reason to skip it, a reason to go slowly, or nothing to watch for.
- Fragile or Sensitive
- Go slowly
- Recent Facial or Laser
- Go slowly
- Prone to Redness
- Go slowly
- Dry or Itchy Patches
- Go slowly
- Recent Shave or Wax
- Go slowly
- Maternity & Nursing
- No caution
Fragile or Sensitive — Use it less often — or stop — if it feels uncomfortable, and keep it off skin that’s broken, cut or sunburned.
Recent Facial or Laser — Wait until your skin feels settled before reintroducing — typically 7 to 14 days after a facial or laser appointment.
Prone to Redness — Try it on a small area first, and use it less often — or stop — if you notice stinging or extra redness.
Dry or Itchy Patches — Keep the rest of your routine well moisturized, and use it less often — or stop — if you notice tightness or itching.
Recent Shave or Wax — Avoid for 24 hours after waxing, threading, or dermaplaning.
Cosmetic strength limits for PHA (Polyhydroxy Acid) where you live#
| Region | Maximum strength |
|---|---|
| United States | No explicit cap |
| Canada | 18% (total mono-AHA, pH ≥3.5) |
| European Union | No explicit cap |
| Great Britain | No explicit cap |
Where a figure appears, that is the maximum strength allowed or advised for pha (polyhydroxy acid) in that market — some are set in cosmetics regulation, others are the ceiling a cosmetic safety panel recommends. The rest set no maximum. Either way these are limits, not targets — the right strength for a formula is the formulator's decision.
Products with PHA (Polyhydroxy Acid)#
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Common questions about PHA (Polyhydroxy Acid)#
When should you apply PHA (Polyhydroxy Acid)?
- A leave-on step: after cleansing, before your moisturizer.
How often can you use PHA (Polyhydroxy Acid)?
- Up to daily, all over, not the eye area.
Where do you apply PHA (Polyhydroxy Acid)?
- All over, not the eye area. Keep it off your lips too.
Does PHA (Polyhydroxy Acid) make skin more sensitive to the sun?
- No. PHA (Polyhydroxy Acid) is not flagged as increasing sun sensitivity.
What should you not use with PHA (Polyhydroxy Acid)?
- Space it apart from Eye-area retinol, Other exfoliants, Retinoids and Vitamin C.
Who should avoid PHA (Polyhydroxy Acid)?
- Go slowly with Fragile or Sensitive, Recent Facial or Laser, Prone to Redness, Dry or Itchy Patches and Recent Shave or Wax.
Is there a cosmetic limit for PHA (Polyhydroxy Acid)?
- Only some regions set one. The maximum strength for PHA (Polyhydroxy Acid) in a cosmetic is 18% (total mono-AHA, pH ≥3.5) in Canada. No maximum is set in the United States, the European Union and Great Britain. A cap is a limit on the rules, not a signal to use more.
Related ingredients#
How we check this#
Everything on this page traces to the sources listed below — regulators' own publications and published studies. Where the evidence does not answer a question, it is left unanswered.
Our review is AI-assisted and is not a named expert's opinion. Last reviewed August 7, 2026.
Think something here is out of date or wrong? Email us at wiki@skinintelligence.ai with your reasoning and where you read it. We read what people send, and we update the page when the sources support it.
Regulators and official bodies · 11
- S1Health Canada. Cosmetic Ingredient Hotlist — Prohibited and Restricted Ingredients (list), entry "Alpha-hydroxy acids, including polyhydroxy acids and bionic acids with alpha hydroxyl groups, and their salts". — fetched 2026-08-04.
- S2Cosmetic Ingredient Review Expert Panel. Safety Assessment of Glycolactones as Used in Cosmetics. Final Report, released 12 October 2022.
- S3Cosmetic Ingredient Review. Glycolactones — Tentative Report, March 2022.
- S4US FDA. Guidance for Industry: Labeling for Topically Applied Cosmetic Products Containing Alpha Hydroxy Acids as Ingredients, January 2005.
- S5US FDA. Alpha Hydroxy Acids (cosmetic ingredient page).
- S6SCCNFP. Position Paper concerning the Safety of Alpha-Hydroxy Acids, SCCNFP/0370/00, adopted 28 June 2000.
- S7SCCNFP. Updated Position Paper concerning Consumer Safety of Alpha-Hydroxy Acids, SCCNFP/0799/04, adopted 25 May 2004.
- S8European Commission, CosIng. Ingredient GLUCONOLACTONE, CAS 90-80-2, EC 202-016-5. Functions: CHELATING, SKIN CONDITIONING. No Cosmetics Regulation provisions; no SCCS opinions.
- S9European Commission, CosIng. Ingredient LACTOBIONIC ACID, CAS 96-82-2, EC 202-538-3. Function: BUFFERING. No Cosmetics Regulation provisions; no SCCS opinions.
- S10Regulation (EC) No 1223/2009, Annex III as retained in Great Britain, legislation.gov.uk.
- S11US FDA. Prohibited & Restricted Ingredients in Cosmetics..
Studies and references · 24
- S12Berardesca E, Distante F, Vignoli GP, Oresajo C, Green B. Alpha hydroxyacids modulate stratum corneum barrier function. Br J Dermatol. 1997;137(6):934-8. PMID 9470910.
- S13Hunt MJ, Barnetson RS. A comparative study of gluconolactone versus benzoyl peroxide in the treatment of acne. Australas J Dermatol. 1992;33(3):131-4. PMID 1303072.
- S14Bernstein EF, Brown DB, Schwartz MD, Kaidbey K, Ksenzenko SM. The polyhydroxy acid gluconolactone protects against ultraviolet radiation in an in vitro model of cutaneous photoaging. Dermatol Surg. 2004;30(2 Pt 1):189-95. PMID 14756648.
- S15Grimes PE, Green BA, Wildnauer RH, Edison BL. The use of polyhydroxy acids (PHAs) in photoaged skin. Cutis. 2004;73(2 Suppl):3-13. PMID 15002656.
- S16Edison BL, Green BA, Wildnauer RH, Sigler ML. A polyhydroxy acid skin care regimen provides antiaging effects comparable to an alpha-hydroxyacid regimen. Cutis. 2004;73(2 Suppl):14-7. PMID 15002657.
- S17Briden ME. Alpha-hydroxyacid chemical peeling agents: case studies and rationale for safe and effective use. Cutis. 2004;73(2 Suppl):18-24. PMID 15002658.
- S18Yu RJ, Van Scott EJ. Alpha-hydroxyacids and carboxylic acids. J Cosmet Dermatol. 2004;3(2):76-87. PMID 17147560.
- S19Draelos ZD, Green BA, Edison BL. An evaluation of a polyhydroxy acid skin care regimen in combination with azelaic acid 15% gel in rosacea patients. J Cosmet Dermatol. 2006;5(1):23-9. PMID 17173568. No abstract in PubMed or Europe PMC..
- S20Green BA, Yu RJ, Van Scott EJ. Clinical and cosmeceutical uses of hydroxyacids. Clin Dermatol. 2009;27(5):495-501. PMID 19695482.
- S21Tasic-Kostov M, Savic S, Lukic M, Tamburic S, Pavlovic M, Vuleta G. Lactobionic acid in a natural alkylpolyglucoside-based vehicle: assessing safety and efficacy aspects in comparison to glycolic acid. J Cosmet Dermatol. 2010;9(1):3-10. PMID 20367666.
- S22Kornhauser A, Coelho SG, Hearing VJ. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clin Cosmet Investig Dermatol. 2010;3:135-42. PMID 21437068 / PMC3047947.
- S23Kantikosum K, Chongpison Y, Chottawornsak N, Asawanonda P. The efficacy of glycolic acid, salicylic acid, gluconolactone, and licochalcone A combined with 0.1% adapalene vs adapalene monotherapy in mild-to-moderate acne vulgaris: a double-blinded within-person comparative study. Clin Cosmet Investig Dermatol. 2019;12:151-61. PMID 30858720.
- S24Tasić-Kostov M, Lukić M, Savić S. A 10% Lactobionic acid-containing moisturizer reduces skin surface pH without irritation — an in vivo/in vitro study. J Cosmet Dermatol. 2019;18(6):1705-10. PMID 30859734.
- S25Algiert-Zielińska B, Mucha P, Rotsztejn H. Comparative evaluation of skin moisture after topical application of 10% and 30% lactobionic acid. J Cosmet Dermatol. 2018;17(6):1096-100. PMID 29318715.
- S26Algiert-Zielińska B, Mucha P, Rotsztejn H. Effects of lactobionic acid peel, aluminum oxide crystal microdermabrasion, and both procedures on skin hydration, elasticity, and transepidermal water loss. J Cosmet Dermatol. 2019;18(5):1463-74. PMID 30661294.
- S27Algiert-Zielińska B, Mucha P, Rotsztejn H. Lactic and lactobionic acids as typically moisturizing compounds. Int J Dermatol. 2019;58(3):374-9. PMID 30270529.
- S28Jarząbek-Perz S, Dziedzic M, Rotsztejn H, Kołodziejczak A. Evaluation of the effects of 10% and 30% gluconolactone chemical peel on sebum, pH, and TEWL. J Cosmet Dermatol. 2023;22(12):3305-12. PMID 37335807.
- S29Jarząbek-Perz S, Dziedzic M, Kołodziejczak A, Rotsztejn H. Split-face evaluation: Gluconolactone plus oxybrasion versus gluconolactone plus microneedling. The effects on skin parameters. Skin Res Technol. 2023;29(6). PMID 37357656 / PMC10209840.
- S30Gentili G, Perugini P, Bugliaro S, D'Antonio C. Efficacy and safety of a new peeling formulated with a pool of PHAs for the treatment of all skin types, even sensitive. J Cosmet Dermatol. 2023;22(2). PMID 35796684 / PMC10087944.
- S31Peng Y, Mao M, Huang Z, Zhao H, Li Y, Jian D. Comparison of Efficacy and Willingness to a 5% Gluconolactone-Based Topical Serum and Intense Pulsed Light in Mild Erythema of Rosacea: A Paired Control Study. J Cosmet Dermatol. 2025;24(3). PMID 40111222. ChiCTR2400087665.
- S32Warowna M, Strzelecka A, Kręcisz B. Influence of Lactobionic Acid on Hydration and Elasticity Parameters in Women Aged 30-40 and 50-60 Years in Comparison to Mandelic Acid. J Clin Med. 2025;14(5):1619. PMID 40095547.
- S33Bruce S, Roberts W, Teller C, Colvan L. The Effects of a Daily Skincare Regimen on Maintaining the Benefits Obtained from Previous Chemical Resurfacing Treatments. J Drugs Dermatol. 2016;15(9):1145-50. PMID 27602981.
- S34Puigdemont A, Furiani N, De Lucia M, Carrasco I, Ordeix L, Fondevila D, Ramió-Lluch L, Brazis P. Topical polyhydroxy acid treatment for autosomal recessive congenital ichthyosis in the golden retriever: a prospective pilot study. Vet Dermatol. 2018. PMID 29786154. (Canine; cited nowhere above as human evidence — recorded because it is the only keratinisation-normalisation study for a PHA and a future reviewer will find it.).
- S35Zhu M, He X, Zhu Z, Lynch S, Wang H, Zhou X, Tu Y, Steel A, Hsu KC, Niu Y, Cho A, Hashimoto M, Yan X, Su M, Wang W. The effect of a serum containing acetyl hexapeptide-8, dipeptide diaminobutyroyl benzylamide diacetate and gluconolactone on skin biomarkers, wrinkles and skin texture: ex vivo and clinical studies. Int J Cosmet Sci. 2026. PMID 41668671.
