Glycerin - Is it the BEST humectant hydrator for skin?

Is Glycerin Secretly the BEST hydrator for your skin?

The world is never short of glitzy new ingredients that promise you your dewiest self. In the humectants category (water-loving ingredients that hydrate your skin), you may have heard of hyaluronic acid, snail mucin, or other exotic seaweed extracts. These ingredients usually come with impressive claims (ie. “holds up to 1000x its weight in water!”) or exotic origin stories with extra skin benefits (filled with 57819473 amino acids and minerals!). But recently, an unlikely candidate has become a buzzy hydrator on the interwebs – good ol’ glycerin. And in our chemists’ opinion, this unassuming ingredient is actually pretty deserving of the buzz. So! Is this simple little guy the BEST humectant all along?! How much glycerin do you really need? How does it compare with other sexier-sounding ingredients like hyaluronic acid? Let’s dive into the data shall we?

What does glycerin do for your skin?

Glycerin is a molecule that is sometimes referred to as “glycerine” or “glycerol”. It’s everywhere in nature! In fact, chemically speaking, it is the “backbone” of a lot of fatty substances that exist in nature called triglycerides. Glycerin is considered a sugar alcohol, but definitely not of the drying kind. It’s a versatile ingredient with many different uses from medical, food, and of course skincare. 

In terms of skincare, glycerin is simply a humectant (learn more about other key components of a good moisturizer here!). It draws moisture into the skin, helping skin stay hydrated through the entire day. In addition to hydration, there are studies indicating that in addition to being a potent water grabber, glycerin can also wedge itself in your stratum corneum, helping skin feel pliant and soft. 

While hydration isn’t an area that typically will have a ton of clinical data, luckily for us, glycerin is one of the most studied ingredients in this category. In fact, in terms of instant hydration, it’s even been tested to outperform other common humectants. In one study, 10% glycerin was benched against 10% propylene glycol and 10% urea in the same base cream in a 3 hour study. After 3 hours, the glycerin group was at a much higher hydration level than the other groups. So in a nutshell, glycerin is a fantastic ingredient for that instant, daily hydration. But is it truly the BEST humectant? 

Glycerin vs. Hyaluronic Acid - Who Reigns Supreme?

If you’re looking for hydrators, you’re bound to come across hyaluronic acid (HA). HA has essentially been marketed as the holy grail of hydration for the past decade or so. Just like glycerin, hyaluronic acid is a humectant known for its ability to retain moisture and keep skin hydrated. So how does glycerin compare with hyaluronic acid?

Structurally speaking, the two molecules are very different. Compared to a polymer like hyaluronic acid, glycerin is a pretty petite molecule. Glycerin is about 92 daltons whereas common forms of HA found in skincare go up to 2 million daltons in size! This means that hyaluronic acid is fantastic at staying on the surface of skin and hydrating the skin’s surface. On the other hand, glycerin’s smaller size allows it to wedge deeper into the skin providing effective daily hydration as well as a soft, supple skin feel. In fact, in most instant hydration studies, glycerin at concentrations of 10% and higher are simply one of the most potent at raising skin hydration level. On the other hand, hyaluronic acid appears to have more going for it in terms of long term skin barrier help. In our humble chemists’ opinion, a well-rounded routine can benefit from having both. This strategic mixing of humectants with different properties is actually the philosophy we took when formulating our hydration champion Aquafix

Battle of the Hydrators: Glycerin vs. Urea

While there isn’t a ton of data that directly compares glycerin to hyaluronic acid, there are quite a few studies that looked at how glycerin performs in comparison with another humectant, urea. In one such study, they looked at how a 4% urea cream would perform against a 20% glycerin cream over 4 weeks. Interestingly, while glycerin was able to improve immediate hydration, urea was much more effective at reducing severe symptoms of dry skin such as scaling, itching, and redness. This shows that while glycerin is one of the best instant hydrators you can have in your routine, it is not the end-all-be-all holy grail to solve your skin barrier issues. The key takeaway? Again, a blend of effective ingredients is the way to go here! If you want to hear more about the glycerin vs. urea comparison, we actually discuss these in a dedicated glycerin podcast episode!

Finding the Best Glycerin Product for Your Skin

So! Is it an absolute must to have glycerin in your routine? Yes! Whether you have oily skin or dry skin, glycerin is a fantastic addition to your hydration game. But wait! Before you run out and grab a dedicated glycerin serum, double-check the ingredient lists of all the skincare you’re currently using. Glycerin is a cosmetic chemists’ favorite ingredient. Meaning - there’s a very high chance that you already have glycerin in your essence, serum, moisturizer, sunscreen, etc. If you’re still wondering whether or not you’ve optimized this ingredient in your skincare routine, here are some tips on finding the best glycerin product for your skin.

Glycerin Concentration to Target.

Glycerin is a relatively high-use level ingredient. You’ll find it on the market from 5% to 20% or sometimes even neat and naturally you might be wondering if there’s a BEST percentage for glycerin to aim for. The good news is that many studies do look at glycerin’s efficacy at various concentrations. In one such study, they tested skin hydration level after applying 3 varying formulas: a pure water placebo, a 5% glycerin-water mixture, and a 15% glycerin water mixture and found that the 15% level performed significantly better at raising skin moisture level. 

However, given that glycerin is not the most glamorous ingredient out there, it’s actually pretty difficult figuring out whether or not you’re getting enough of it. Generally speaking, you want to look for a moisturizer or serum that has glycerin at the second or third spot on that ingredient list. That’s a pretty solid indication that the product contains ~5% glycerin. If you’re using more than 1 product in your routine that contains glycerin (outside of your cleanser), chances are you’re getting enough. But if you want to be SURE of the glycerin level you’re getting, check out products like our Aquafix Hydrating Water Gel (5% + other humectants)  and Experiment Beauty’s Super Saturated (30% glycerin centric). 

Pro Tip! Glycerin by itself at high concentrations isn’t necessarily a bad thing. However, keep in mind that an exorbitant amounts glycerin or glycerin neat (DIYers) can get heavy and sticky which can make your routine a lot less layerable. 

Glycerin Product Landscape

Key Takeaways

While glycerin may not be a showstopper in the skincare ingredient realm, it is one of the best instant hydrators that can enhance anyone’s skincare routine. However, depending on your skin goals, glycerin alone will not suffice. It does fall short for those who don’t just want daily hydratio but also want to improve our skin barrier health long term (that’s all of us). This is why at the end of the day it’s important to get a good blend of humectants. We consider glycerin to be a trusty sidekick to make sure your skin stays plump and moist day-in-day-out.


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