Hydroxyisohexyl-3-cyclohexene carboxaldehyde (HICC) known as
Lyral is a frequent
allergen. It is used in more than 50% of marketed
deodorants. The aim of the present study was to determine elicitation thresholds for HICC under simulated conditions of
deodorant use. 15 patients with previously diagnosed contact
allergy to HICC were patch tested with 5 solutions of HICC-scented and HICC-unscented
deodorants. Patients and 10 healthy controls performed a use test in the axillae using
deodorants scented with HICC in increasing concentrations and unscented
deodorants as control. The concentration of HICC was increased every second week (200, 600, and 1800 p.p.m.) until either a reaction developed or for 6 weeks. 14 patients completed the study, and all developed unilateral
eczema from the HICC-containing
deodorant, while controls were all negative (P= 0.004). In 9/14 patients, a positive use test developed during the first 2 weeks to the
deodorant containing 200 p.p.m. HICC. Positive correlations were found between the day of positive use and patch test threshold concentration of the HICC solutions (r= 0.71, P= 0.01) as well as the patch test thresholds of the HICC-scented
deodorants (r= 0.74, P= 0.007). In conclusion, HICC elicits
allergic contact dermatitis in a high proportion of sensitized individuals at common usage concentrations in
deodorants.