Vegetable glycerin may sound more like something you'd find in the kitchen than in your bathroom, but it's actually one of the more commonly-used skincare ingredients out there. (Though, fun fact, in its purest form, it actually is safe to consumer orally, and sometimes actually is found in food. But we digress.) When it comes to your skin, it's one of the best hydrators out there, attracting water to and holding it in the skin. Here, Nava Greenfield, a board-certified dermatologist at Schweiger Dermatology Group in New York City, and cosmetic biochemist Stacy Steinmetz, creator of StimuNail, give us the lowdown on this popular ingredient.
Meet the Expert
Type of ingredient: Humectant
Who should use it: Anyone and everyone, though it's especially great for those prone to dry skin.
Main benefits: Attracts water to and holds in the skin, leaving it feeling and looking smooth and supple.
How often can you use it: Daily or even multiple times per day.
Works well with: Vegetable glycerin works well with most ingredients, says Steinmetz, who points out that its silky, liquid texture has the added benefit of lending a nice consistency to many formulas. Greenfield adds that, because of its humectant properties, it can also be used before and after more potentially irritating ingredients, such as retinoids, that tend to dry out the skin.
Don't use with: According to the experts we spoke with, there are no ingredients known to interact negatively with vegetable glycerin.
What Is Vegetable Glycerin?
"Glycerin is a sugar alcohol that's clear, colorless, and odorless," explains Steinmetz. It can be derived from animal products, plants, or petroleum, she adds, noting that vegetable glycerin is simply the kind that comes from plants. (Common ones include soy, palm, and coconut oils.) While most ingredient labels won't specify the type of glycerin used, vegetable glycerin is more common, says Greenfield, who adds that it often appears in anti-aging products, moisturizers, shampoos, and conditioners. Still, if you're a vegan and/or want to make sure you're getting the plant-based variety, seek out products labeled as vegan. Though again, there really is no difference in the types.
Benefits of Vegetable Glycerin for Skin
Vegetable glycerin is a humectant—it works by drawing water into the skin and keeping it there, which is great for improving both skin barrier function and skin health in general, says Greenfield. Steinmetz explains that it actually pulls moisture from both the air and your skin, helping boost hydration levels in two different ways. On top of that, it also imparts a dewy, supple feel to the skin, making it appear plump and healthy, she points out.
So, how does it differ from other humectants, such as hyaluronic acid, the other most common one? It comes down to their differing chemical structures. "The chemical structure will ultimately determine how many water molecules it can attract and hold onto, which in turn determines how efficient the ingredient is at moisturizing the skin," explains Greenfield. "Glycerin specifically has the ability to hold onto a few water molecules at one time, and, because glycerin sticks strongly to itself, those water molecules don't evaporate from the skin," she adds. (That being said, it's worth noting that hyaluronic acid can hold onto more water than glycerin is.)
Side Effects of Vegetable Glycerin
There aren't many to speak of, really. Of course, an allergy to any ingredient is always possible, but any side effects are rare. It's generally very well-tolerated by most, including those with sensitive skin.
How to Use It
Here's the thing: Vegetable glycerin/glycerin is such a prevalent ingredient that there's already a very high likelihood it's in the moisturizer you're using, so don't drive yourself nuts seeking out products with glycerin. Again, it's probably going to be in any lotion or cream. That being said, if you do want to maximize the effects, try applying any product with glycerin (or any humectant, for that matter) onto skin that's slightly damp or in a humid environment; think a steamy bathroom post-shower. This will give the ingredient more water to grab onto, ultimately making it more effective. Greenfield notes that products with glycerin are also nice to use in tandem with more irritating active skincare ingredients (retinoids, we're looking at you) because of the hydrating benefits. Steinmetz points out that pure vegetable glycerin is also readily available online and that you can easily add a few drops to pretty much any hair, skin, or body product to up the moisturizing benefits. Or, try dabbing it directly onto areas like chapped lips or cracked heels before layering a thicker balm or cream on top for an extra boost of hydration, she says.