How Effective is Glycerine?

Glycerine is one of the most ubiquitous ingredients in personal care products and can be found in everything from anti-aging serums to night creams, from antidandruff shampoos to conditioning hair masks. According to INCI Beauty it is present in 55.4% of all products listed on their extensive database.   Why is it so widespread? It is inexpensive and effective on both skin and hair.

What is Glycerine?

Glycerine, also sometimes called Glycerol, is a colourless, odourless, and viscous (thick) liquid that is non-toxic both orally and on the skin.  It has inherent anti-microbial and anti-viral activity so is often incorporated into wound healing formulas. Perhaps confusingly, it can also be found in bacterial growth media where it functions as a fuel source. It mixes very well with water, is not bio accumulative and is biodegradable. Glycerine can be made from both petroleum derivatives or plant and animal fats. Most glycerine used in the cosmetic industry is vegetable derived and may be listed specifically as Vegetable Glycerine.



Benefits & Function

The official INCI functions of glycerine are:

Denaturant : Makes cosmetics unpleasant. Mainly added to cosmetics containing ethyl alcohol

Hair conditioning : Leaves hair easy to comb, soft, soft, and shiny and / or confers volume, lightness, and shine

Humectant : Maintains water content of a cosmetic both in its packaging and on the skin

Oral care/hygiene agent : Provides cosmetic effects to the oral cavity (cleaning, deodorisation, and protection)

Skin conditioning : Maintains skin in good condition

Skin protecting : Helps to avoid the harmful effects of external factors on the skin

Solvent : Dissolves other substances

Viscosity controlling : Increases or decreases the viscosity of cosmetics

Perfuming : Used for perfume and aromatic raw materials

Within skincare, the most common reason for including glycerine into a formula for end-user benefit is for the Skin Protecting, Skin Conditioning and Humectant/Moisturising properties. It is hygroscopic as it retains water molecules which is key to its impressive moisturising performance. Glycerine forms part of the skins Natural Moisturising Factor (NMF) along with other compounds you may have heard of before including amino acids, sodium PCA and urea. Introducing glycerine into a skincare routine can help replenish the NMF and keep skin looking and feeling at its best.

Glycerine has other functions however that may go unnoticed. It is a great solvent, a good stabiliser and is also bacteriostatic. These along with demonstrable skin benefits makes glycerine a true ‘work horse’ ingredient that is often overlooked as it is common and doesn’t have a fancy sounding name. A final function which is rarely mentioned is the role glycerine can play as a ‘penetration enhancer’ which is an ingredient which helps other ingredients reach more deeply into the skin. This is very important for many actives which tend to bunch at the skin surface and not provide the level of benefit they could be. This is a very valuable attribute and arises partly because glycerine itself has a small molecular weight of 92g/mol so penetrates the skin while ‘dragging’ other ingredients with it and partly because it softens the skin allowing other ingredients to penetrate more easily.

It is a fantastic choice for formulators as it is a readily available material and is incredibly well tolerated across all skin types meaning it functions just as well and safely in an eczema cream as it does in a hydrating night serum.



Is Glycerine Safe for the Skin?

Glycerine, like Panthenol, is a very skin safe and popular moisturising ingredient. There are no known side effects of glycerine, but like almost all chemicals, rare cases of allergic reaction have been reported especially when used in high concentrations.

Oddly, I have seen an increasing number of clients, still a minority, request that glycerine is not included in formulations but when pushed to detail why, the response is usually some form of ‘I read online that it is bad’. The exact opposite is true. While high concentrations of glycerine can feel tacky, the material is rarely included at those sort of levels in skin care products and there are technical ways to offset this. One of the only situations where it might make sense to remove glycerine from a formula is in the context of personal lubrications. This is because glycerine can be used as a fuel source for certain types of bacteria, which, in rare cases may interfere with the microbiome health of the vagina which good lubrications should attempt to avoid. As glycerine is such a good emollient and humectant it can often make up to 30% of a lubrication formula.

How effective is it?

Numerous studies have shown the potent moisturising and humectant effect of glycerine:

Moisturising – This study demonstrates that glycerine penetrates the stratum cornea and resides there for a long time where it continues to attract moisture, cementing it’s use as an effective moisturiser. It has an excellent balance of skin penetration and retention characteristics.

Moisturising – This study compared a glycerine and urea/sodium chloride-based moisturising cream and found that glycerine (at a very high 20%) was the more appropriate choice as it was considered less irritating but provided similar relief to skin dryness and itchiness.

Healing/Anti-Microbial – While perhaps not directly healing, glycerine has been shown to be anti-microbial at high concentration. The creation of a bacteriostatic environment is beneficial to the wound healing process.

Anti-Inflammatory – Glycerol (Glycerine) was shown here to be a very useful active when included alongside other ingredients that are known to be irritating such as Sodium Lauryl Sulphate (SLS). Glycerol showed significant anti-irritant and anti-inflammatory properties when used alongside irritants.

Penetration Enhancer – This study showed that inclusion of glycerine in a drug delivery patch significantly increased drug penetrance in the skin by both increasing drug solubility and softening the skin.

What does Glycerine pair well with?

Glycerine  plays very well with a multitude of other base or active ingredients, and it is very stable across temperatures and pH fluctuations. There are no known contraindications.

It combines particularly well with the ingredients below, either to enhance their function, or balance potential side effects. For example, Acids are great exfoliators and cleansers but can leave skin dry. Glycerine helps combat this dry feeling.

Hyaluronic Acid – humectant

Panthenol – humectant, soothing

Niacinamide – smoothing

Retinoids – skin conditioning

Acids – exfoliating

Sulphates – cleansing, foaming

Summary

Glycerine is a widely available natural ingredient that is extremely well tolerated, has a wealth of useful benefits and one which combines well with a huge number of other actives. An incredible material for skin care users and formulators alike.

Key Benefits:

·      Potently hydrating

·      Very well tolerated

·      Inexpensive

·      Supports wound healing

·      Is antimicrobial

·      Combats irritating ingredients

·      Appropriate for all skin types
 

This post was written by our Chief Scientist, Dr. Edward Jones