A clear, plant-derived humectant that draws water into skin; the backbone of moisturisers, washes and hand creams.
What it is
Glycerin is a clear, syrupy liquid, usually made from plant oils. It pulls water into the outer layer of skin and keeps it there, so skin feels softer and less tight. It is gentle, and at higher levels it is the hero of classic hand creams for hard-working hands.
Good for
Dry skinDehydrated skinDry handsSensitive skin
How it works
Glycerin is a humectant, and skin also makes its own glycerol, which helps keep the barrier flexible and resilient. Higher levels give a stronger effect.
Ratings
Evidence
5/5
Well established, with consistent clinical benefit in reviews.
Gentleness
5/5
Not an irritant or sensitiser at cosmetic levels.
Formulation difficulty
1/5
Water-soluble and stable, though it can feel tacky at high levels.
Cost
1/5
Inexpensive commodity.
Popularity
5/5
Present in a large share of products, with over 15,000 US uses.
Pairs and cautions
Pairs well with
In a routine. Pairing in one formula depends on matching pH windows.
Unscheduled with no limit. Claims to protect or moisturise dry, chapped skin are cosmetic; claims to heal or repair damaged skin make the product a therapeutic good.
United States
At 20–45% glycerin is an OTC skin-protectant drug active, so hand creams can be sold as drugs claiming to protect chapped or cracked skin, with a Drug Facts panel.
European Union
No limit on glycerin, but diethylene glycol, a toxic contaminant, is banned except as a trace of up to 0.1%, so buy pharmacopoeia-grade glycerin with a DEG test.
Canada
Health Canada requires glycerin in leave-on and oral products to meet a recognised pharmacopoeia's diethylene glycol limit, such as the USP glycerin monograph.
In the lab
Specifications
Typical use level
3–10%0525%
Solubility
Water-solubleAlcohol-soluble
Most lotions use 3–7%, while intensive hand creams go to 15–40%. Above about 10% it can feel tacky unless balanced with silicones or esters.
INCI
Glycerin
Also known as
Glycerol, Vegetable glycerine
Origin
plant-derived
Lab notes
Solubility and phase
Water phase. It also mixes with alcohol.
Stability
Specify a pharmacopoeia grade such as USP or EP, and keep drums sealed, as it is hygroscopic. It lowers water activity and improves freeze–thaw resistance.
Regulatory, Australia
Cosmetic ingredient in Australia, with no restriction. CIR (2019) found it safe as used in cosmetics.
Claims to take care with
Cosmetic claims include 'hydrates', 'moisturises' and 'softens', while 'heals cracked skin' or 'repairs damaged skin' are therapeutic. 'Vegetable', 'palm-free' or RSPO claims need supplier documentation, as plant grades come from palm, coconut or rapeseed oil.
