What is Glycerin?
Glycerin, also known as glycerol, is a colorless, viscous liquid that is commonly used in skincare products and dermatological applications. While it is an endogenous molecule (native to the skin) it can be both animal and vegetable derived, created from the saponification of lipids. Vegetable glycerin is often derived from natural vegetable oils including soybean, coconut, and palm oil. Glycerin is a well studied and widely used humectant known for its ability to improve skin hydration, enhance cutaneous elasticity, and repair the epidermal barrier.
Glycerin has a 3 carbon chain backbone with 3 hydroxyl groups with these groups acting as moisture magnets. Glycerin can actually absorb its own weight in water. As a humectant, it draws moisture from the air to the skin, helping to keep skin hydrated and plump therefore reducing the appearance of fine lines and wrinkles. Not only can it improve skin texture and appearance but it can also soothe and calm irritated skin. Due to its low molecular weight, it can penetrate the skin easily through Aquaporin-3 transport channels to restore skin’s moisture.
Overall, glycerin is a versatile and effective ingredient in skincare products, and its ability to hydrate, improve the overall health and appearance of the skin, as well as protect the skin from external stressors make it a popular choice among cosmetic formulators, dermatologists, and consumers alike.
What Does Glycerin Do to the Skin?
Glycerin has been shown to help improve the skin’s barrier function which can help protect it against irritating stimuli and environmental stressors such as pollution and cold dry climate. It prevents the phase transition of the stratum corneum lipids which in turn keeps moisture from escaping, also referred to as transepidermal water loss. Applying glycerin can help restore endogenous glycerin creating a moisture reservoir in the skin to help maintain stratum corneum hydration and skin barrier properties. By maintaining both skin hydration and barrier function, the skin is more soft, supple, elastic, and smooth.
A product containing glycerin can be classified as a skin protectant per the FDA when glycerin is used at concentrations between 20-45% and formulated according to the Over-the-Counter (OTC) Monograph M016: Skin Protectant Drug Products for Over-the-Counter Human Use. Glycerin used as an active pharmaceutical ingredient at the required use levels can temporarily protect and help relieve chafed, chapped, or cracked skin and lips while helping protect from the drying effects of wind and cold weather.
Benefits of Glycerin:
Glycerin is a highly versatile and beneficial ingredient for the skin due to its unique properties. It is a well substantiated material with many peer-reviewed studies highlighting its safety and skin attributes. Some of the benefits of glycerin for skin include:
Improves Skin Barrier Function: By improving the skin barrier function the skin is better protected from external stressors such as pollution and irritants, keeping skin moisture loss and skin irritation at a minimum.
Increases Hydration: Glycerin is a humectant that diffuses osmotically into the stratum corneum and epidermis while pulling water along with it, increasing the water-holding capacity in the skin.
Relieves Skin Dehydration: As a skin protectant it protects and helps relieve chafed, chapped, or cracked skin and lips from the drying effects of wind and cold weather.
Addresses Signs of Aging: Glycerin has anti-aging properties and has been shown to improve skin elasticity and reduce the appearance of fine lines and wrinkles.
Non-Irritating: Glycerin is a gentle and non-irritating ingredient, making it suitable for use on even the most sensitive skin types.
Healing Properties: Glycerin can help to soothe and calm irritated or inflamed skin. It is also useful in promoting wound maintenance and reducing the appearance of scars.
Compatibility: Glycerin is compatible with a wide range of other skincare ingredients and can be used in a variety of skincare formulations and formats without issue.
How Does Glycerin Work?
Native to the skin, glycerin is a by-product of triglyceride breakdown in sebum by sebaceous gland-associated lipase. Production of glycerin in these pilosebaceous follicles is crucial for stratum corneum hydration. Glycerin can be supplemented and applied on the skin to aid in hydration and increase the water-holding capacity of the skin. Due to its small molecular weight it can be transported through aquaporin channels in the stratum corneum and hydrate below the top superficial layers of skin. It also inhibits lipid phase transition in the stratum corneum helping to preserve skin barrier function and limit water loss.
Concentration Levels & Recommended Usage for Glycerin:
Glycerin is a versatile ingredient that can be used in a wide range of skincare products at different concentrations. Glycerin is found in many products and when cosmetically used generally ranges in concentration from 2% to 10%. When used as the API in skin protectant products, the use level is 20-45%. Glycerin itself is viscous and sticky so high concentrations have the potential to make a product feel tacky and unpleasant on the skin.
Not only is glycerin used in leave-on products but it can benefit the skin in rinse of products such as body washes and facial cleansers. Glycerin can limit irritation and dryness by reducing surfactant-skin interaction. Surfactant micelles have the potential to solubilize lipids in the skin leading to dryness and to denture skin proteins leading to irritation. Glycerin hinders the ability of surfactant micelles to penetrate through stratum corneum aqueous pores thus limiting irritation and dryness. One study showed that the addition of only 10% glycerin was able to reduce the radius and pore number density of these aqueous pores, preventing micelles from penetrating and disturbing the skin.
Glycerin works well in combination with other hydrating and moisturizing ingredients to maximize skin health.
Is it Okay to Use Glycerin Daily?
Glycerin is considered non-toxic, non-irritating, and non-sensitizing and is safe for use in skincare products. The Cosmetic Ingredient Review Board (CIR) noted a study in which glycerin diluted to 50% with water was non irritating to subjects with dermatitis when applied under occlusion for 20-24 hours. Another study they noted found a cream containing 65.9% glycerin to be non-sensitizing to human subjects. It is important to note that some people with very sensitive skin may be allergic or sensitive to glycerin so a patch test before using a product containing glycerin is recommended. Overall, when used appropriately and in accordance with product instructions, glycerin is a safe and effective ingredient for daily use in skincare products.
Who Should Use Glycerin?
Glycerin is great for dry and dehydrated skin types but is well-tolerated by all skin types.
Individuals with dry skin may benefit the most from using glycerin-containing products, as glycerin is an excellent moisturizing ingredient that can help to hydrate and soften dry skin. Those with mature skin may find improvement in the skin texture and reduction in the appearance of fine lines and wrinkles.
Glycerin is non-irritating, non-comedogenic, non-greasy, and won’t clog pores. This is crucial for those with oily and combination skin looking to still maintain optimal skin hydration without a product leaving a heavy or oily residue.
Sensitive and reactive skin types can also benefit from using glycerin-containing products. Glycerin can help to soothe and hydrate sensitized skin caused by dehydration and a compromised skin barrier.
Who Should Not Use Glycerin?
While glycerin is generally tolerated by all skin types, high levels of glycerin can provide a warming effect which may not be desired for those with sensitive skin. Start with products that have lower levels of glycerin. It is always important to patch test a new product before using it on the entire face or body, and to discontinue use if any adverse reactions occur.
What Skincare Ingredients Pair Well with Glycerin?
Glycerin is a versatile ingredient that can be used in a wide range of skincare products, and can be paired with other ingredients to enhance its benefits.
Moisturizers: Glycerin is a popular ingredient in moisturizers due to its excellent hydrating properties. It pairs well with other humectant ingredients such as hyaluronic acid, beta-glucan, and aloe vera but also pairs well with occlusive ingredients such as ceramides, shea butter, and petrolatum to give next level moisturization.
Serums: Glycerin can also be used in serums to help boost hydration and promote a healthy, glowing complexion. It can be paired with other active ingredients such as vitamin C, niacinamide, and retinol to improve the appearance and texture of skin.
Cleansers: Glycerin works well with surfactants to minimize their potential to dry or irritate the skin.
Masks: Glycerin can also be used in masks to help hydrate and nourish the skin. It pairs well with other soothing ingredients such as chamomile, oat extract, and honey to create a mask that can help to calm and normalize skin hydration.
Haircare: When incorporated into a shampoo or conditioner it can help improve the elasticity of the hair shaft and hydrate the scalp.
Are There Any Ingredients that Should Not Be Used with Glycerin?
When formulating a product with glycerin, chemists need to be aware of solubility. Glycerin is water soluble and not incorporated into facial oils, ointments, or anhydrous products. Aside from solubility, glycerin plays well with most ingredients and won’t inactivate any particular ingredients or reduce efficacy of products. However, glycerin can act as a slight penetration enhancer by increasing the solubility of actives and hydrating the stratum corneum. That means when combined with ingredients that are more prone to causing irritation such as alpha hydroxy acids and retinoids, glycerin can cause further penetration and therefore increase potential of irritation.
Glycerin is a relatively safe and well-tolerated ingredient that can be used in a wide range of skincare products and be beneficial for all skin types.
DISCLAIMER: All skin care articles are intended to help educate on specific ingredients and skin care topics. Our articles are written to be informative and informational. Any reference to a specific patient experience is not a medical suggestion for treatment. Please note that any Prequel products with referenced ingredients are formulated for Cosmetic Use Only and NOT intended as replacements for physician advice and/or pharmaceutical product recommendations.