Contact Allergy to Fragrance Mix II and Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde: A Retrospective Study by International Contact Dermatitis Research Group

Abstract

Background: Fragrance mix II (FM II) is included in the baseline patch test series recommended by the International Contact Dermatitis Research Group (ICDRG). Hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) is the most important sensitizer of the 6 fragrance materials included in FM II. Besides being a part of FM II, HICC is also tested separately in the ICDRG baseline series.Objectives: The aim of the study was to investigate the prevalence of contact allergy to FM II and HICC in 2012-2016 with a focus on simultaneous reactions and the percentage of missed contact allergy to HICC provided that only FM II had been tested.Patients and Methods: A total of 25,019 consecutive dermatitis patients in 13 dermatology clinics representing 12 countries in 5 continents were patch tested with FM II and HICC in the baseline series.Results: Contact allergy to FM II and HICC was found in 3.9% and 1.6%, respectively. For FM II, the frequency varied from 1.5% to 7.6% in different centers. The corresponding range for HICC was 0.2% to 3.6%. Simultaneous contact allergy to FM II and HICC was noted in 1.4% with the range 0.2% to 2.6%. Seventy-seven patients (0.31%) with contact allergy to HICC did not test positively to FM II. The range for missed HICC allergy by testing only FM II in the different centers would be 0.04% to 0.74%. The ratio between the contact allergy rates for FM II and HICC was similar for all centers, except for Montreal having significantly more contact allergy to FM II than to HICC.Conclusions: The frequency of missed contact allergy to HICC when testing only with FM II was less than 0.5%, therefore questioning the need to test HICC separately in the ICDRG baseline series.

Prevalence, concomitant reactions, and factors associated with fragrance allergy in Thailand

“…Interestingly, recent studies have proposed that patch testing with HICC might not be needed due to the overall low prevalence of positive reactions to HICC 5% pet. alone 23,24 . Our study found that 0.9% of the tested patients reacted to HICC without having a reaction to FM II; this result was three times the corresponding share reported by the ICDRG (0.3%) 23 .…”

“…alone 23,24 . Our study found that 0.9% of the tested patients reacted to HICC without having a reaction to FM II; this result was three times the corresponding share reported by the ICDRG (0.3%) 23 . It might be that allergen exposure levels differ from one country to another, with HICC possibly being used more frequently in products in Thailand.…”

“…Although routine patch testing with additional HICC 5% pet. is no longer recommended by the ICDRG, 23 HICC 5% demonstrated a very high prevalence relative to the frequencies reported for other countries 23 . Patch‐test screening with HICC 5% in our clinic should therefore be observed over an extended period before it is decided whether to remove it from our baseline series.…”

Decrease of contact allergy to hydroxyisohexyl 3‐cyclohexene carboxaldehyde in Europe prior to its ban and diagnostic value

“…7 The gain by testing HICC as an individual allergen in addition to FMII has recently been questioned. 8 In general, an allergen is recommended to be included in the baseline series if at least 0.5% to 1.0% of suspected dermatitis patients react to the allergen. 9 The prevalence of HICC allergy exceeded 1% for the whole time period for both populations, although it decreased to 1% in the year 2019 in the Gentofte population.…”

“…These findings are similar to those reported by others. 8 Hence, HICC does not fulfill the current criteria for inclusion in the European Baseline Series. For optimum performance in diagnosing fragrance contact allergy, routine application of the full set of 26 fragrances currently needing labeling is suggested.…”