Quick Comparison
| Gluconolactone (PHA) | Glycerin | |
|---|---|---|
| Typical Concentration | Concentrations: 4-15%. Can often be used daily even by sensitive skin types. Apply morning or night. No sun sensitivity increase (unlike AHAs). pH range: 3.5-4.5. | Concentrations: 2-10% in most products (often higher in moisturizers). Pure glycerin is too sticky — always diluted in formulations. Works best below 20% concentration. No maximum daily use limit. |
| Application | Topical (serum, toner, cream). Gentle enough for daily use on most skin types. | Topical (present in virtually all moisturizers, serums, and toners). Apply as part of regular skincare routine. |
| Research Papers | 4 papers | 9 papers |
| Categories |
Mechanism of Action
Gluconolactone (PHA)
Gluconolactone hydrolyzes desmosomal proteins and glycosaminoglycan bonds between corneocytes in stratum corneum, promoting desquamation. Large molecular size (178 Da vs glycolic acid 76 Da) means slow, even penetration through lipid bilayer — no irritation-causing 'hot spots' of concentrated acid. Gentle, sustained exfoliation. Six hydroxyl groups per molecule make it a potent humectant, forming hydrogen bonds with water and drawing moisture into stratum corneum. Chelates iron and copper ions, reducing metal-catalyzed free radical formation. Has antioxidant properties. Unlike AHAs, does not increase UV sensitivity. Lactone ring hydrolyzes to gluconic acid at skin pH. Ideal for sensitive skin, rosacea, those intolerant of glycolic or salicylic acid.
Glycerin
Glycerin (glycerol) is a small three-carbon polyol (92 Da) that penetrates the stratum corneum via intercellular lipid and transcellular routes. It acts as a humectant through osmotic mechanisms—creating a concentration gradient that draws water from the atmosphere (when humidity >65%) and from deeper epidermal layers. Glycerin upregulates aquaporin-3 (AQP3), a glycerol-permeable water channel in keratinocyte membranes that facilitates water and glycerol transport. It supports the natural moisturizing factor (NMF)—amino acids, lactate, and urea that maintain stratum corneum water-holding capacity. Glycerin modulates keratinocyte differentiation and may enhance lipid lamellae organization. Mild antimicrobial activity occurs through osmotic stress. Clinical studies demonstrate hydration efficacy comparable to or exceeding hyaluronic acid.
Risks & Safety
Gluconolactone (PHA)
Common
Essentially none — one of the most tolerated exfoliants. Slight stickiness.
Serious
None.
Rare
Mild irritation in extremely reactive skin.
Glycerin
Common
Stickiness at high concentrations. May cause mild breakouts in some acne-prone individuals (varies by person).
Serious
None. Extremely safe.
Rare
Allergic reaction is extremely rare.
Full Profiles
Gluconolactone (PHA) →
A polyhydroxy acid (PHA) — the gentlest class of chemical exfoliants. Gluconolactone has a very large molecular size, so it works extremely slowly on the skin surface without penetrating deeply. This makes it ideal for extremely sensitive skin, rosacea-prone skin, and those who cannot tolerate AHAs or BHAs. It also acts as a humectant, drawing moisture into the skin as it gently exfoliates.
Glycerin →
The most effective and best-studied humectant in skincare. Glycerin (glycerol) is a small molecule that penetrates the stratum corneum readily, drawing water from the atmosphere and deeper skin layers to hydrate the outer skin. Present in virtually every moisturizer and many serums. Studies show it rivals or outperforms hyaluronic acid for hydration efficacy at a fraction of the cost.