What it is

Peptides from silk fibroin or sericin, used as a cosmetic ingredient. In 2020 the Cosmetic Ingredient Review panel assessed ten silk protein ingredients and found eight safe as used, with insufficient data for two (MEA-hydrolyzed silk and silkworm cocoon extract). Johnson 2020

How it works

It is proposed to form a film. We located no hair mechanism study.

What the studies show

Eight of ten silk protein ingredients were judged safe as used, with insufficient data for two. Johnson 2020
A Finnish screening of about 2,200 people for reactions to hair-conditioner protein hydrolysates found the reactions came from a hydrolysed collagen ingredient. Niinimaki 1998
No hair-fibre efficacy data exist.

Side effects and safety

Allergy risk is reported as low overall. It is animal-derived, so not vegan.

Bottom line

A cosmetic gloss ingredient that has not been shown to repair anything. We are very unsure of any benefit.

Studies 2

Johnson W Jr et al. Safety assessment of silk protein ingredients as used in cosmetics. Int J Toxicol. 2020

Design: review

Result: Eight of ten silk protein ingredients were safe as used; there was insufficient data for MEA-hydrolyzed silk and silkworm cocoon extract.

Read the study ↗

Niinimaki A et al. Contact urticaria from protein hydrolysates in hair conditioners. Allergy. 1998

Design: other
People: 2,200
Who: about 2,200 patients screened in Finland

Result: Twelve patients, all women with atopic dermatitis, reacted to a hydrolysed collagen derivative in hair conditioners with contact urticaria.