Polyglutamic Acid
INCI · Polyglutamic Acid · also PGA, gamma-polyglutamic acid
How it works
Polyglutamic acid is a biopolymer produced through bacterial fermentation, often from Bacillus subtilis, the same organism traditionally used to ferment natto. Its long, water-loving polymer chains bind moisture at the skin's surface and slow water evaporation more effectively, gram for gram, than hyaluronic acid. It also forms a thin, flexible film that can temporarily smooth the look of fine lines and texture, giving skin an immediate plumped appearance.
The evidence
In vitro and clinical hydration studies suggest polyglutamic acid can retain moisture significantly better than hyaluronic acid alone, and it performs well in combination with it. I consider the hydration mechanism well understood, even though large-scale independent clinical trials remain less abundant than for hyaluronic acid, which has a longer commercial history. What convinces me clinically is how consistently patients report a lasting plumpness compared to hyaluronic-acid-only formulas, particularly in dry or heated indoor air.
Suitability
- Suitable for all skin types, including sensitive and acne-prone skin
- Especially useful for dehydrated skin that still needs a lightweight texture
- Non-comedogenic and considered safe in pregnancy
- Good option for those who find hyaluronic acid alone insufficient in dry climates
Concentration
Effective formulations typically use 0.1% to 0.5% polyglutamic acid, occasionally up to 5% in concentrated humectant serums. Because it works synergistically with other humectants, layering it beneath a moisturizer often outperforms using it alone, and I rarely see additional benefit from pushing concentration higher than the formulation calls for.
Conflicts & combinations
- Pairs excellently with hyaluronic acid for compounded hydration
- Works well under squalane or ceramide-based moisturizers to lock in water
- No known conflicts with acids, retinoids, or vitamin C
- A smart addition to any routine that already feels dry from active ingredients
- dryness
- dullness
- uneven texture
- Effective from
- 0.5%
- Max safe
- 5%
Is polyglutamic acid better than hyaluronic acid?
It can hold more water per gram, but the two work well together rather than one replacing the other.
Can polyglutamic acid cause breakouts?
It is non-comedogenic and considered safe for acne-prone skin.
Is polyglutamic acid safe during pregnancy?
Yes, it is generally considered safe, as it is a humectant with no known systemic absorption concerns.
Does polyglutamic acid help with fine lines?
Its surface film can temporarily smooth the look of fine lines, though this is a hydration effect rather than a structural anti-aging change.
Can I use polyglutamic acid every day?
Yes, it is gentle enough for twice-daily use in most routines.