Euxyl K 400: a new sensitizer in cosmetics

Area of Science:

• Dermatology
• Cosmetic Science
• Allergology

Background:

• Euxyl K 400 is a widely used cosmetic preservative containing 1,2-dibromo-2,4-dicyanobutane and 2-phenoxyethanol.
• The increasing prevalence of cosmetic products containing Euxyl K 400 necessitates an understanding of its allergenic potential.

Purpose of the Study:

• To investigate the prevalence of contact allergy to Euxyl K 400 in patients with suspected cosmetic allergy.
• To identify the specific components of Euxyl K 400 responsible for sensitization.
• To assess the cross-reactivity with other cosmetic ingredients.

Main Methods:

• Patch testing of 2057 patients with Euxyl K 400 (2.5% pet.) and ethanol.
• Follow-up patch testing with lower concentrations of Euxyl K 400 (0.5% pet.) and phenoxyethanol (5% pet.) in a subset of patients.
• Provocative use testing with a cosmetic lotion containing Euxyl K 400 (0.1%).

Main Results:

• A positive patch test to Euxyl K 400 occurred in 24 patients (1.2%), with cosmetic products identified as the source of sensitization in 8 cases.
• One patient showed sensitization to phenoxyethanol, while only 3 exhibited mild reactions to Euxyl K 400 (0.5%).
• Five of 11 patients reacted positively in a provocative use test with a lotion containing 0.1% Euxyl K 400.

Conclusions:

• Euxyl K 400 is a relevant contact allergen in cosmetic allergy.
• Phenoxyethanol appears to be less frequently implicated than the mixture.
• Euxyl K 400 should be incorporated into standard patch test series for diagnosing cosmetic allergies.