Immediate and delayed patch test reactions to individual fragrances have been identified in the Thai population, according to a study published online June 8 in the Journal of the American Academy of Dermatology.

Nutchaya Amornruk, M.D., from Chulalongkorn University in Bangkok, and colleagues examined the prevalence of an immediate patch test reaction to fragrance in patients with fragrance allergic contact dermatitis in a prospective study. A total of 291 patients were given standard patch tests for allergic contact dermatitis, and those with positive reactions were asked to undergo additional patch tests to 28 different fragrance substances for immediate and delayed reactions.

The researchers found that the most frequently encountered substances in positive immediate reactions and standard (delayed) patched tests were cinnamic aldehyde and cinnamic alcohol. Reactions to benzyl alcohol, sorbic acid, and coumarin were observed more frequently in immediate patch tests than standard patch tests.

"Cinnamic aldehyde and cinnamic alcohol were found to be the most common fragrance allergens eliciting immediate reactions in the Thai population in our current study," the authors write. "Given that both fragrance substances were major components of spices and essential oils that were frequently used in a variety of Asian foods, beverages, and personal care products such as mouthwash, it was expected that a high prevalence of immediate allergic reaction to these substances would exist in the Thai population."

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