HumectantDraws in waterIn every formula

Glycerin

Glycerin · INCI Glycerin

Glycerin is the ingredient nobody puts on the front of a bottle. It has been used for well over a century, and we are rather fond of it.

It is among the best-evidenced ingredients in skincare.

Glycerin, the humectant that draws water into the skin in every formula.

What it is

Glycerin is a humectant, which means it attracts water and holds on to it. Applied to the skin, it draws moisture up from the layers beneath and in from the air around you, and keeps it in the outer layer, which is where dryness is felt. That is the whole mechanism, and it is about as well demonstrated as anything in cosmetic science.

It works particularly well alongside oils. Our formulas are mostly water, with plant oils making up a minority of each. The glycerin draws water into the skin, and the oils slow its escape.

What it does in our formulas

Both of glycerin's jobs are about water.

It pulls water into the skin

Glycerin is a humectant: it attracts water and holds on to it. Spread on the skin, it draws moisture up from the deeper layers and in from the air, and keeps it in the outer layer where dryness is felt. This is one of the most thoroughly demonstrated effects in cosmetic science, and it is why glycerin is in nearly every moisturiser ever made.

Well characterised

It supports the skin's own upkeep

The enzymes that let dead cells detach and the processes that keep the barrier in order all need moisture to work. The research suggests that keeping the surface hydrated helps the skin's own upkeep, and glycerin is the most reliable way we know to do that.

Well characterised

What the research does not show

Glycerin is more often disparaged than over-claimed.

Marketed as It is a cheap filler, and a serious product would use something fancier

Glycerin is inexpensive because it is easy to make. It is one of the most rigorously demonstrated ingredients in the field, and a moisturiser that left it out to make room for a more marketable humectant would be a worse moisturiser.

Marketed as In dry weather it steals water from your skin

You will see this repeated confidently. It comes from the fact that a humectant, used neat in very dry air, can in principle pull water from the skin rather than into it. In a finished moisturiser, with oils slowing water loss, there is little evidence that it happens.

On the label and in the range

Glycerin appears in every one of our formulations, high in the ingredient list, because it does real work and needs to be present in real quantity to do it. If you have been taught to read a high-ranking cheap ingredient as a sign of cost-cutting, this is the one to unlearn that on. The exact percentage is published on each product page.

Is it suitable for me?

Glycerin has a long safety record in cosmetics, is well tolerated on even very sensitive skin, and carries no restrictions under UK or EU cosmetic law. Ours is plant-derived, so it suits a vegan routine. Glycerin can be made from animal fat or from petroleum, and it is worth knowing that, and worth asking about anywhere it is not stated.

Vegan-friendlySensitive-skin suitableWell tolerated

Glycerin is among the gentlest ingredients in cosmetic use. As with anything new, if your skin reacts easily it is worth patch testing first.

The research behind this page

We review the published literature. We do not conduct the studies below.

Fluhr JW, Darlenski R, Surber C. Glycerol and the skin: holistic approach to its origin and functions. Br J Dermatol 2008;159(1):23-34. →
Milani M, Sparavigna A. The 24-hour skin hydration and barrier function effects of a hyaluronic 1%, glycerin 5%, and Centella asiatica stem cells extract moisturizing fluid. Clin Cosmet Investig Dermatol 2017;10:311-315. →
Man MQ, Elias PM. Stratum corneum hydration regulates key epidermal function and serves as an indicator and contributor to other conditions. J Eur Acad Dermatol Venereol 2019;33(1):15-16. →

Found in every Biotaderm formulation Shop the range