Hydration / Barrier

Betaine

INCI: Betaine · CAS 107-43-7

Betaine (trimethylglycine) is a naturally derived humectant and osmolyte used in skincare to hydrate and to help protect skin cells against osmotic and environmental stress.

INCIBetaine
CAS107-43-7
Also known asTrimethylglycine
Use leveltypically 0.5–5%
Solubilitywater-soluble
pH / stabilitystable across a broad range
RegulatoryListed in EU CosIng

What it does

  • Hydrates with a light, non-tacky feel.
  • Helps protect cells against osmotic stress (osmoprotection).
  • Softens the sensory feel and can reduce irritation potential of a formula.

How it works

Betaine is a compatible-solute osmolyte: cells accumulate it to maintain water balance under stress without disrupting proteins. In cosmetics it is widely documented as a gentle humectant that also improves skin feel and can reduce the sting of surfactant systems. It complements other osmolytes such as ectoin and trehalose.

Use level

Typical use level
typically 0.5–5%

Commonly 0.5–5%; a versatile, inexpensive humectant that improves feel at modest levels.

Formulation considerations

  • Water-soluble; add to the water phase.
  • Stable and broadly compatible, including in cleansers where it reduces harshness.
  • Non-tacky, which makes it useful for lightweight textures.

What it pairs with & what to avoid

Pairs well with

  • Glycerin, hyaluronic acid, trehalose, ectoin
  • Surfactant systems (reduces irritation)
  • Most actives

Use with care / avoid

  • No notable incompatibilities

Regulatory status

Betaine is listed in the EU CosIng database and is a well-established, gentle cosmetic ingredient.

Common questions

What does betaine do in skincare?

It hydrates with a light feel and acts as an osmolyte that helps protect cells against water stress; it also improves sensory feel.

What percentage of betaine is used?

Typically 0.5–5%.

Is betaine good for sensitive skin?

Yes; it is gentle and is often added to cleansers to reduce harshness.

Related monographs

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