Watch Out, Hyaluronic: Polyglutamic Acid Is Here to Hydrate

Hyaluronic acid has been the main character of hydrating skincare at least since 2019, when Eva Longoria sounded the ingredient out on national TV. I can’t tell you the number of times a derm has told me, “hyaluronic acid holds 1,000 times its weight in water.” Seriously, finding a serum, moisturizer, or even a skin tint that don’t brag about having HA somewhere in the formula is a small feat. But lately, a newly buzzy ingredient has been trying to find a spot on my bathroom shelf: polyglutamic acid, or PGA.And before the word acid sends you running for the hills (or to your skin barrier cream), polyglutamic acid isn’t a harsh exfoliating acid like glycolic or salicylic acid. Rather, like hyaluronic, it’s a humectant, meaning its job is to help attract and retain water for softer, plumper-looking skin. “Polyglutamic acid (PGA) is a high-molecular-weight water-soluble peptide/polymer produced through bacterial fermentation,” says board-certified dermatologist Divya Shokeen, MD. In simpler terms, “it is a powerful humectant capable of holding up to four to five times more moisture than hyaluronic acid,” she says. Take that in for a second... four to five times more than our hugely-loved HA.It’s also increasingly appearing in hydrating serums and moisturizers alongside—you guessed it—hyaluronic acid. Which raises the obvious question: Do we actually need another hydrating acid? And is PGA coming for HA’s crown, or are the two better together? Is HA more popular for a good, results-based reason, or did it just benefit from a better PR team? As we head into fall, I already know my skin is bound to get drier, which means I need the scoop on getting as much hydration as possible. So, I asked three dermatologists to break down all the facts about this “superhydrator.” Plus, stick around for PGA product recommendations at the end.What is polyglutamic acid?Glad ya asked. Despite its relatively recent buzz in skincare, polyglutamic acid itself isn’t brand new on the scene. At the simplest level, “it helps attract and hold water at the skin’s surface,” says board-certified dermatologist Rishi Chopra, MD. “This helps replenish dry, dull skin and can make crepiness and fine lines look smoother and plumper.” It’s a part of the humectant ingredient category, meaning it helps attract water and retain hydration. You’ll find humectants (like PGA, HA, glycerin, and urea) in skin care products that are meant to be moisturizing, like face creams, serums, and certain cleansers.To get a little more into the science of PGA specifically, it’s “made up of chains of glutamic acid, an amino acid that occurs naturally in the body,” explains board-certified dermatologist Alexandra Bowles, DO. “It’s typically produced through bacterial fermentation and was first identified in natto, a fermented soybean food.”What does polyglutamic acid do for your skin?In terms of benefits, hydration is the headliner here. PGA attracts and binds water to your skin’s surface, says Dr. Bowles. But what does that actually mean for your skin? “That can translate into skin that feels softer, smoother, and less tight, and fine lines related to dehydration may look less noticeable,” she says—all things I’m interested in for my skin, personally! Essentially, if you’re dealing with dry or dehydrated skin, this is an ingredient that should pique your interest. Sadly, though PGA can minimize the look of some of those fine lines and wrinkles, it’s not actually treating them—as in, it’s not necessarily rebuilding collagen or reversing skin aging. Rather, it “forms a flexible, protective film on the skin’s surface,” says Dr. Shokeen, which, in addition to the benefits Dr. Bowles also mentioned, also results in a dewy, smooth finish on your skin.Is polyglutamic acid better than hyaluronic acid?Okay, here’s the question you’re probably thinking (it was the first place my mind went, at least): If hyaluronic acid already hydrates your skin, why should you care about polyglutamic acid? And which one is better?Surprisingly, the answer isn’t necessarily that you should dump one for the other. Although both are humectants, they aren’t identical, which means they provide similar but, again, not identical, benefits. You can actually use them together.PGA is “a very large molecule,” explains Dr. Bowles, so “it tends to stay on the surface of the skin rather than penetrating deeply.” As you probably already know, hyaluronic acid comes in various molecular weights, which means it can deliver hydration to the surface of your skin as well as to much deeper layers depending on the size(s) of the HA molecule used in a given product formulation. So, HA is ideal for that “deep multi-depth hydration,” says Dr. Shokeen. “If your skin barrier needs surface-level moisture retention, smoothing, or a dewier finish, PGA is fantastic. Using both together gives the ultimate hydration experience.”So, rather than thinking of this as a skincare face-off, your derm may actually recommend using them together. “If you want to stick with the ingredient with the most evidence, hyaluronic acid has a longer clinical track record, but for most people, you don’t have to choose, because both can be effective and are generally well-tolerated,” says Dr. Chopra. “Since many people already have HA in their routine, PGA can be another way to add an extra layer of hydration.”Well, sorry to anyone hoping for some humectant drama: PGA probably isn’t “replacing” hyaluronic acid, just adding one more tool to your hydration toolbox.How do you use polyglutamic acid?The nice thing about a hydration-focused ingredient is that incorporating it into your skincare routine is really easy. PGA shouldn’t cause irritation, so you don’t need to worry about starting slowly or alternating days (of course, it’s always a good idea to patch test any new product upon first use, especially if you have easily reactive skin). Plus, it plays well with those potentially irritating ingredients like retinol and vitamin C, so you can use it right alongside those.PGA can be found in serums, moisturizers, masks, and other hydrating products, so how you use it will depend on the formula you choose. If you’re using a serum, you’ll want to apply it after cleansing and before moisturizer, but follow the directions on your specific formula. If it’s in moisturizer form, use it after any serums and toners.Who should and shouldn’t use polyglutamic acid?The derms I spoke with agree that PGA is pretty much for anyone and everyone. Still, there are some people who might benefit from it more than others. It “tends to be well-suited to dry, dehydrated, and mature skin, and it may also be a good option for people with sensitive skin, since it’s generally gentle and not known to be irritating,” says Dr. Bowles. “It’s usually considered non-comedogenic, so many acne-prone patients can use it as well.”There aren’t many people who need to avoid it entirely, but “some may find the film it leaves behind feels heavy or sticky, particularly on very oily skin or in humid climates,” says Dr. Bowles. Of course, if you have an allergy to polyglutamic acid, this hydrator isn’t gonna be for you. And if you have very sensitive skin, Dr. Chopra reminds us that you should make sure to take note of the other ingredients in the formula so you don’t have any adverse reactions.Polyglutamic acid products that Cosmo editors and derms love:Meet the expertsRishi Chopra, MD, is a Harvard fellowship-trained, board-certified cosmetic dermatologist. He is the Skin Longevity Director at Hudson Dermatology & Laser Surgery in NYC, and recognized for his expertise in lasers, injectables, and regenerative aesthetics.Divya Shokeen, MD is a board-certified dermatologist, UCLA graduate, and the founder of OSVI Dermatology and Surgical Institute in Manhattan Beach, CA. In addition to medical and surgical dermatology, Dr. Shokeen is a hair transplant surgeon specializing in non-surgical hair restoration.Alexandra Bowles, DO, is a board-certified dermatologist at MONA Dermatology in Cincinnati, OH.Why trust Cosmo?Catharine Malzahn is a contributing beauty writer at Cosmopolitan with five years of experience researching and writing skincare stories. She has dealt with dry skin for much of her 20s and loves trying a new hydrating skincare product.Catharine Malzahn is a contributing beauty writer at Cosmopolitan and was previously the beauty assistant at Good Housekeeping, Woman's Day, and Prevention.