Glossary

Humectant

Written by Reviewed by the SYNC editorial team Published Last reviewed Editorial standards

Humectant — an ingredient that attracts and binds water into the upper layers of the skin, drawing moisture from deeper layers or the surrounding air. This helps keep the surface hydrated, plump, and supple.

Key points

  • Humectants work by chemically attracting water molecules and holding them within the stratum corneum.
  • Common humectants include glycerin, hyaluronic acid, sodium PCA, urea, propylene glycol, and honey.
  • In very dry or low-humidity environments, humectants can pull water from deeper skin layers, so pairing them with an occlusive helps lock hydration in.
  • They are found in many serums, toners, and moisturizers to boost surface hydration and improve skin feel.

Frequently asked

Should I apply humectants to damp or dry skin?

Humectants generally perform best on slightly damp skin, giving them water to bind to. Following with an occlusive or emollient helps seal in the moisture.

Can humectants dry out my skin?

In very dry air, humectants may draw water from deeper skin layers rather than the environment, which can feel drying if moisture then evaporates. Layering an occlusive on top helps prevent this.

Related topics

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.

Encyclopedia

Further reading

This entry was written and checked against the sources below. They are published by clinical and scientific bodies, they are listed most readable first, and each one opens in a new tab. They are background for the whole entry rather than footnotes to individual sentences.

  1. Emollients and Moisturizers (Moisturisers) DermNet NZ Clinical guidance dermnetnz.org
  2. Moisturizers StatPearls (NCBI Bookshelf) Reference text ncbi.nlm.nih.gov
  3. Moisturizers: The Slippery Road PubMed Central Peer-reviewed, open access pmc.ncbi.nlm.nih.gov
  4. Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics - a double-blind, randomized and controlled study PubMed Peer-reviewed (abstract) pubmed.ncbi.nlm.nih.gov
  5. The structure of normal skin DermNet NZ Clinical guidance dermnetnz.org
  6. Anatomy, Skin (Integument) StatPearls (NCBI Bookshelf) Reference text ncbi.nlm.nih.gov

SYNC does not publish medical advice. Nothing here replaces a consultation with a doctor or a pharmacist about your own skin.