What is it?
A conditioning ingredient made by breaking down (hydrolyzing) protein from flaxseed, the seed of Linum usitatissimum, also called linseed, into smaller fragments. “Hydrolyzed flax protein” is not an official EU ingredient name; the closest listed names are Hydrolyzed Linseed Extract, a skin conditioner, and Hydrolyzed Linseed Seed, listed for hair and skin conditioning, film forming and holding moisture. It appears in hair care such as conditioners.
Key information
- Hydrolyzed flax protein is not a name in the EU cosmetic ingredient database; the closest entries, Hydrolyzed Linseed Extract and Hydrolyzed Linseed Seed, carry no restrictions.
- Neither the Cosmetic Ingredient Review nor the EU's Scientific Committee on Consumer Safety has assessed hydrolyzed flax or linseed ingredients.
- Flaxseed allergy is uncommon but can be severe; a 2024 review found 13 published cases of IgE-mediated flaxseed allergy, most with severe reactions.
- For hydrolyzed wheat protein, CIR requires small peptides after a soap with a large-peptide wheat hydrolysate sensitized more than 2,100 people in Japan.
More information
To make hydrolyzed ingredients, plant material is split by acid, enzymes or another method into smaller molecules. The EU cosmetic ingredient database defines Hydrolyzed Linseed Seed as the hydrolysate of flaxseeds and lists it as film forming, hair and skin conditioning, skin protecting and humectant (moisture-holding). Hydrolyzed Linseed Extract is described only as a hydrolyzed linseed extract, used for skin conditioning. Neither entry carries restrictions.
Neither the Cosmetic Ingredient Review (CIR) nor the EU’s Scientific Committee on Consumer Safety has assessed these ingredients, and we found no reports of skin reactions to hydrolyzed flax protein in cosmetics.
The main question for any hydrolyzed protein is allergy. Flaxseed allergy is generally considered uncommon but is increasingly recognized: a 2024 review found 13 published cases of IgE-mediated flaxseed allergy, most involving severe reactions, and recent reports point to a seed storage protein called conlinin (Lin u 1) as a culprit allergen. Hydrolyzed proteins can also sensitize through the skin when their peptides are large. In Japan, a facial soap containing a large-molecule hydrolyzed wheat protein sensitized more than 2,100 people, and eating wheat foods caused anaphylactic reactions in about 55 percent of them. The CIR Expert Panel concluded that hydrolyzed wheat protein is safe only when its peptides average 3,500 daltons or less. CIR has not set any comparable limit for flax, which it has not reviewed.
People with a known flaxseed allergy can look for Hydrolyzed Linseed Extract, Hydrolyzed Linseed Seed or hydrolyzed flax protein on labels.
Sources: European Commission CosIng: Hydrolyzed Linseed Extract; European Commission CosIng: Hydrolyzed Linseed Seed; Porto Biomedical Journal (2024), via PMC: Flaxseed anaphylaxis: an emerging allergen; CIR: Safety Assessment of Hydrolyzed Wheat Protein and Hydrolyzed Wheat Gluten as Used in Cosmetics (final report, 2014)
