Betaine
A sugar-beet humectant that softens harsh cleansers — and is NOT the same as the allergen cocamidopropyl betaine
INCIBetaine
- Category
- Humectant
- Risk level
- low
- What it is
- An osmolyte (trimethylglycine) from sugar beet that helps cells hold water
- Cleanser softener
- Blunts the irritation of sulfate and amphoteric surfactants
- NOT cocamidopropyl betaine
- Plain "betaine" is a gentle humectant; cocamidopropyl betaine is a separate surfactant with a higher allergy rate
- Tolerability
- Allergy essentially unheard of; used in baby/sensitive formulas
Look for these names on ingredient lists
This ingredient may appear under any of these names:
Commonly found in
Possible reactions
- No documented allergic reactions
- No irritation at cosmetic concentrations
- Often added specifically to reduce surfactant irritation
- Used in baby and sensitive-skin products
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Highly rated products that feature Betaine in their ingredient list.
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Always scan the actual label before use — formulations change.
What is betaine?
Betaine — also called trimethylglycine (TMG) — is a small molecule (glycine with three methyl groups) found in sugar beets, spinach, and many organisms, where it acts as an osmolyte: it helps cells hold onto water under stress (salty soil, cold). Cosmetic betaine is extracted from sugar-beet processing, making it a low-cost, vegan humectant.
It does two jobs in skincare: as a humectant it draws water into the upper skin and leaves a soft after-feel, and as a cleanser softener it sits alongside surfactants and reduces their potential to irritate.
Why it's almost universally safe
Betaine has one of the cleanest safety profiles in cosmetics — it's a molecule your own body uses in metabolism and that you eat in everyday foods. Safety panels rate it safe at all cosmetic concentrations (usually 0.5–5%), and true allergic contact dermatitis is essentially unheard of.
This naming trips people up. Plain betaine (trimethylglycine) is the gentle humectant on this page. Cocamidopropyl betaine (CAPB) is a different ingredient — a coconut-derived surfactant that is a recognised contact allergen. If you're tracking a "betaine" reaction, check which one is on the label; they're not interchangeable.
How to handle it
- No need to seek it out — it works quietly in many products you already use.
- Look for it in "gentle"/sensitive cleansers, usually top 5–7 ingredients.
- Pair with richer humectants (glycerin, HA, panthenol) in dry climates.
- Choose betaine cleansers if SLS dries you — they're typically far less stripping.
- Don't confuse it with CAPB.
Alternatives
- Richer hydration: glycerin, hyaluronic acid, sodium PCA.
- Even gentler cleansing: decyl/coco-glucoside, sodium cocoyl isethionate.
- Reacting to a betaine cleanser? suspect the surfactant/fragrance/preservative, not the betaine.
The bottom line
Plain betaine is a benign sugar-beet humectant that makes cleansers milder and adds light hydration — allergy essentially nonexistent. The single most useful thing to remember is that it's not cocamidopropyl betaine, the surfactant allergen with a similar name.
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