Cocamidopropyl Betaine
Cocamidopropyl betaine (CAPB) is a mild, coconut-derived surfactant used to cleanse and boost foam in shampoos and body washes. It is generally gentle, but manufacturing impurities can make it a contact allergen — it was named Allergen of the Year in 2004 — so it is flagged for sensitive skin.
CAPB is an amphoteric surfactant made from coconut oil, often paired with harsher surfactants to make a formula milder and creamier.
CAPB itself is mild, but two impurities from its synthesis (amidoamine and dimethylaminopropylamine) are the actual sensitisers behind reported reactions. The American Contact Dermatitis Society named it Allergen of the Year in 2004, so people with sensitive skin or a known CAPB allergy should be aware of it.
Who this affects
Caution
- Sensitive skin & eczema: A coconut-derived surfactant whose impurities are a recognised contact allergen.
Frequently asked questions
CAPB is a mild amphoteric surfactant widely used to boost foam and reduce the harshness of stronger cleansers, and safety reviews conclude it is safe as used in cosmetics. A published safety assessment found a wide margin of safety at up to 6% in leave-on products and 30% in rinse-off products. It induces only relatively mild skin irritation for most users.
CAPB is a coconut-oil-derived surfactant, so it is plant-based in origin, though it is chemically processed rather than "raw" natural. Because it is made from coconut and not from animal sources, it is generally considered suitable for vegan formulations. Sourcing and certification still depend on the individual manufacturer.
Yes, it can cause allergic contact dermatitis in a minority of people, which is why the American Contact Dermatitis Society named it Allergen of the Year in 2004. Sensitised people can develop eczema-like reactions or eye irritation, confirmed by dermatologist patch testing. It remains a relatively uncommon allergen given how widely it is used.
Evidence points to manufacturing impurities rather than pure CAPB as the main sensitisers, specifically amidoamine and 3-dimethylaminopropylamine (DMAPA). People who patch-test positive to amidoamine or DMAPA are advised to avoid CAPB-containing products. Better-purified CAPB is expected to carry a lower sensitising risk.
CAPB is one of the milder surfactants and is often added specifically to soften harsher cleansers, so most sensitive-skin users tolerate it well. However, if you have a known patch-test allergy to CAPB, amidoamine or DMAPA, you should avoid it. A dermatologist’s patch-test result is the authoritative guide, not the ingredient list alone.
Sources
American Contact Dermatitis Society — Cocamidopropyl betaine named Allergen of the Year (2004)