Common Name(s): Polyhydroxy acid (pha),gentle large-molecule exfoliant,sensitive skin aha

CAS Number: N/a

DESCRIPTION

What It Does: Provides gentle keratolytic exfoliation, skin brightening, and humectant moisture retention simultaneously — with a skin-irritation profile significantly lower than glycolic or lactic acid from slower penetration kinetics.

Why It's Used: The gold standard for sensitive skin chemical exfoliation — phas provide aha-class exfoliation efficacy in fitzpatrick iv–vi and rosacea skin types where glycolic acid is too aggressive.

How It Works: Multiple hydroxyl groups on the pha molecule slow sc penetration (fick's law: d ∝ mw^-0.7) providing gentler keratolytic action. the hydroxyl groups also bind water providing simultaneous humectancy and chelate ca²⁺ to disrupt desmosomal adhesion for exfoliation.

Typically Found In: Sensitive skin,exfoliating toners,post-procedure

TECHNICAL DETAILS

Primary Category: Active ingredient – alpha hydroxy acid (aha)

Secondary Functions: Brightening,collagen stimulation

Application Areas:

Typical Concentration Range: 1%–15%

SOURCING & ETHICS

Vegan Status: Conditional - feedstock declaration required

Halal Status: Unverified - feedstock declaration required (plant, animal and petrochemical routes all exist)

Source Notes: Fermentation-derived or synthetic. ph must be ≤4.0 for aha activity. [audit 2026-07-29 rev2: origin-dependent: the same inci exists in plant, animal and petrochemical versions and the name does not discriminate. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 2/5 – low to moderate

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Photosensitizing – mandatory spf use. start at low frequency.

Safe for Sensitive Skin: Use with caution – spf required

SAFETY & COMPATIBILITY

Safety Profile: Safe at otc concentrations. eu: ≤10% leave-on at ph ≥3.5. mandatory spf advisory.

Works Well With: Niacinamide,ceramides,hyaluronic acid,spf

Avoid Combining With: Retinol in same step; multiple exfoliants simultaneously

SCIENTIFIC NOTE

Phas have a water of hydration shell from multiple oh groups that further slows sc penetration versus equivalent-mw ahas — the combined larger mw and greater hydration shell providing the gentlest keratolytic delivery kinetics of all acid exfoliants.

Last Verified: 2026-03-12

Primary Sources: Cosing database,polyhydroxy acid pha gentle exfoliant review