Korean Polyglutamic Acid Serum: Layer It on Damp Skin
A Korean polyglutamic acid serum helps your skin hold onto water, so apply it to damp skin in your serum step. Topical polyglutamic acid (PGA, or γ-PGA) is a microbial-derived, water-soluble polymer that supports the skin barrier, and a reconstructed-skin study backs that role in the lab. It pairs well with hyaluronic acid.
TL;DR:
A 2025 reconstructed skin study found that 1% polyglutamic acid raised markers linked to barrier strength and water movement, but long term effects remain untested.
Apply it to damp skin after thinner serums, seal it with moisturizer, and use it up to twice daily; add sunscreen in the morning.
Polyglutamic acid can hydrate similarly to hyaluronic acid in model systems, and the ingredients pair well, so choose a serum containing both or glycerin.
Choose watery serums for oily or combination complexions and richer gels for dryness; reactive skin benefits from fragrance free formulas and a patch test.
Table of Contents
What is polyglutamic acid and why do serums use it?
Polyglutamic acid is a water-soluble polymer produced by bacteria such as Bacillus subtilis, and it is rich in carboxylic acid groups that attract and bind water. As a recent study notes, γ-PGA is biodegradable and forms a moisture-retaining layer when applied to skin. That layer is why formulators favor it in lightweight hydrating products.
A few basics help you read labels with confidence:
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Topical versus oral: Healthline explains that topical serums and essences are the right route for skin hydration, while oral PGA supplements serve unrelated medical purposes.
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Molecular weight: PGA comes in different chain lengths. Higher-molecular-weight, water-soluble versions are the ones studied for surface hydration and barrier support.
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Origin: Fermentation with bacteria, and in some research with seaweed-derived substrates, produces the PGA used in cosmetics. A brown algae formulation study explored this route for cream formulations.
In short, a PGA serum works at the surface, where it helps water stay put.
What does the research say about PGA hydration and barrier support?
The strongest evidence we can point to comes from lab models, and it is encouraging without being final. A 2025 study using keratinocytes and a reconstructed skin model tested a high-molecular-weight γ-PGA from a Bacillus subtilis strain.
The researchers reported that topical 1% γ-PGA elevated filaggrin, involucrin, CD44, and AQP3 in a reconstructed skin model compared to control. These are markers tied to barrier strength and water movement in the skin.
The same study saw dose-dependent increases in barrier markers and in hyaluronic acid synthase expression in keratinocytes. In plain terms, PGA appeared to nudge skin cells toward behaviors that support moisture retention.
Formulation research adds a practical angle:
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Commercially available γ-PGA showed hydration effects comparable to hyaluronic acid and glycerol in model systems, according to the brown algae study.
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Some seaweed-derived γ-PGA delivered greater hydration capacity in cream systems, without negative effects on HaCaT keratinocytes.
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Tested concentrations in that work stayed within a modest range, which fits what you see on serum labels.
Keep expectations realistic. These are laboratory and formulation findings, and the authors themselves call for more research on long-term dermatological effects. Think of PGA as a promising hydrating step, not a cure for a damaged barrier.
Which ingredients and formulation cues should you look for?
Start with the ingredient list, because it tells you more than the front label does. Look for “polyglutamic acid” or “γ-PGA” spelled out clearly.
Complementary ingredients that tend to appear in well-built hydrating serums:
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Hyaluronic acid: a familiar humectant that pairs naturally with PGA.
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Glycerin: an inexpensive, reliable water-binder that adds comfort.
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Panthenol: supports a softer, more cushioned feel on the skin.
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Soothing botanicals: centella or similar extracts for skin that reddens easily.
Texture and packaging matter too. Watery serums layer easily under other products, while gel or ampoule textures feel a bit more cushioning and leave a dewy finish. Pumps and opaque bottles help protect actives from air and light, which keeps the formula steadier over time. You can browse options in our serums collection and check each label against this list.
How do you use a PGA serum step by step?
PGA works best on slightly damp skin, since humectants draw on the water already there. Here is the routine we suggest:
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Cleanse your face and pat it mostly dry.
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Apply a hydrating toner or essence while skin is still damp.
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Press a few drops of PGA serum into your face.
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Seal with a moisturizer to keep the water in place.
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In the morning, finish with sunscreen.
On layering, Women’s Health notes that PGA works well with humectants like hyaluronic acid and antioxidants like vitamin C, and that it is best applied late among your serums so it can help lock in moisture over them. Go from thinnest to thickest texture. Our layering guide and daily routine steps cover the full order.
You can use a PGA serum up to twice daily, as Healthline reports. If your skin is sensitive, patch-test on your inner forearm or behind the ear first.
Pro Tip: Mist or tap water onto your face right before the serum. A damp surface gives the humectant more to hold.
How do you choose a Korean PGA serum for your skin?
Use this short checklist when comparing bottles:
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Clear listing: “polyglutamic acid” or “γ-PGA” appears in the ingredients, ideally with a percentage such as 1%.
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Supporting humectants: hyaluronic acid or glycerin sit alongside it.
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Gentle formula: minimal fragrance and alcohol if your skin is reactive.
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Right texture: a watery serum for oily or combination skin, a richer gel for dry skin.
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Honest sizing: compare bottle size to price, and favor brands that show full ingredient lists.
Match the serum to your need. Dehydrated skin often responds well to lightweight layers, while dry or barrier-stressed skin benefits from a PGA serum followed by a cushioning cream. If barrier comfort is your priority, our guide to barrier-repair moisturizers shows what to pair it with, and this explainer on dry skin shows why moisture alone is rarely enough. When in doubt, start with serums from our hydration picks.
Ingredient delivery is a topic of its own. If you enjoy the science of how actives are formulated to reach the body, this partner article on liposomal delivery is a useful companion read, though it concerns supplements rather than skincare.
Where PGA fits in a real routine
Lab evidence for PGA is promising, and that is enough for me to call it worth trying in a hydration-first routine, especially if hyaluronic acid alone has left your skin feeling less than cushioned. I would not treat it as a miracle step. I would treat it as a comfortable, low-drama layer that supports the skin you already have, and the reconstructed-skin findings give that choice a reasonable footing.
Our approach at Le Panda Beauté is to curate authentic Korean hydration and barrier products so you can build a complete routine without guessing.
— Sophie Wong
Where can you buy authentic Korean hydrating serums?
We source every product from trusted Korean distributors and ship directly from South Korea, so you get genuine formulas and quick access to new releases. Free shipping is available on qualifying orders.
Start with our serums collection, then round out your routine from Skin Care, Moisturizers, and Treatments. In the morning, finish with sun care such as Beauty of Joseon Relief Sun: Rice + Probiotics, also available as a double pack, or the Aqua-fresh Rice+B5 version. Explore our Sun Protection, Cleansers, and Makeup pages too. If you want a PGA serum, check the label for “polyglutamic acid” on each product page.
FAQ
What is the best Korean serum for dry skin?
Look for a serum that combines polyglutamic acid with hyaluronic acid and glycerin, then seal it with a moisturizer. Dry skin does best when a water-binding serum is followed by a richer cream, so the serum alone is rarely the whole answer.
Is polyglutamic acid safe for skin?
Topical PGA is widely used in serums and essences, and it is generally applied up to twice daily, as Healthline reports. Patch-test first if your skin is sensitive, and stop using it if irritation appears.
Is hyaluronic acid or polyglutamic acid better?
Neither wins outright. A formulation study found commercially available γ-PGA showed hydration effects comparable to hyaluronic acid and glycerol in model systems, and the two work well together in one routine.
How do you layer PGA with other serums?
Apply it after your thinner serums and before moisturizer, on slightly damp skin. Women’s Health advises placing PGA late among serums so it can help lock in moisture over other humectants.
