Glycerin

Humectant that draws water into skin and strengthens barrier.

Also known as: Glycerol, Glycerin (USP), humectant

What it is

Glycerin is a small, water-soluble polyol (sugar alcohol) derived from plant oils or synthesized from petroleum. It's one of the most widely used and well-tolerated hydrating agents in skincare.

What it does

Glycerin works as a humectant, drawing moisture from the environment and deeper skin layers into the stratum corneum. It also supports the skin barrier by replenishing natural moisturizing factors (NMF) and reducing transepidermal water loss (TEWL). At concentrations of 5–10%, it improves skin hydration, plumpness, and elasticity; higher concentrations can feel sticky but remain effective.

The evidence

Strong clinical evidence supports glycerin's hydrating and barrier-protective effects across multiple studies. It is proven to reduce TEWL, improve skin hydration within hours, and enhance skin feel and appearance in both healthy and compromised skin.

Best for

All skin types, especially dry, dehydrated, sensitive, and barrier-compromised skin; also beneficial for eczema-prone and post-procedure skin.

Pairs well with

Hyaluronic acid, ceramides, niacinamide, peptides, and other humectants and emollients for synergistic hydration and barrier repair.

Use cautiously with

No major conflicts. In very dry climates (low humidity), pure glycerin without occlusive follow-up may draw water from deeper layers; pair with occlusives (oils, butters) to lock in hydration.

Cautions

Generally very safe and non-irritating; no sun sensitivity, pregnancy concerns, or prescription restrictions. Rare contact sensitization reported in highly sensitive individuals.