Protein hydrolysates (PHs) are added to hair-care products (to "repair" broken hair),
soaps, bath
gels, creams, etc. From one to 22 PHs used in hair-care products (
collagen,
keratin,
elastin, milk, wheat, almond, and
silk) were tested in three patient groups: A) 11 hairdressers with hand
dermatitis B) 2160 consecutive adults with suspected allergic respiratory disease subjected to routine skin prick tests C) 28 adults with
atopic dermatitis. In group A, all the 22 PHs were tested with scratch and patch tests. In groups B and C, one to three PHs were tested with prick tests. Positive scratch/prick test reactions were seen in 12 patients from three PHs altogether. All were women with
atopic dermatitis, and all reacted to at least hydroxypropyl trimonium hydrolyzed
collagen (Crotein Q). In three patients, prick and open tests with a hair conditioner containing Crotein Q were performed with positive results. One patient reported contact
urticaria on her hands, and two reported acute
urticaria on their head, face, and upper body from a hair conditioner containing Crotein Q. In seven of the eight studied sera, specific
IgE to Crotein Q was detected. In conclusion, PHs of
hair cosmetics can cause contact
urticaria, especially in patients with
atopic dermatitis.