Polyglutamic Acid
Polyglutamic acid forms a flexible hydrogel film on the skin's surface that holds in water even more effectively than hyaluronic acid does, by some measurements, while also slowing the water loss that would otherwise undo a humectant's work. It's most effective layered under an occlusive like squalane rather than used alone.
How it works
An anionic peptide polymer produced via bacterial fermentation that creates a flexible, highly hydrophilic hydrogel film on the skin surface. It restricts transepidermal water loss while simultaneously inhibiting endogenous hyaluronidase activity to protect internal hyaluronic acid stores.
In practice, applying it and stopping there under-delivers on what it can do — it needs the same damp-skin-then-seal approach hyaluronic acid does to actually hold that water in.
How to introduce it
Wait about 2 minutes before the next step. Judging Polyglutamic Acid before week 4 means judging it before it's had time to actually work — most of what reads as "this isn't doing anything" in the first couple of weeks is just too early to tell.
- Apply to damp skin, then seal with moisturizer — on dry skin in low humidity it can pull water from the skin instead of the air.
Who should be careful
Polyglutamic Acid's safety rating is the lowest tier tracked here — well tolerated by most skin types, including sensitive skin, without a slow introduction.
Questions people ask
A humectant that holds water at the surface even more effectively than hyaluronic acid, by some comparisons — works best sealed in with an oil or moisturizer after.
Most people see a fair result around 4 weeks of consistent use — judging earlier usually means judging too soon.
Either — Polyglutamic Acid works in both a morning and an evening routine.