Methyl isoeugenol is a colorless to pale yellow clear liquid; its odor type is spicy and its odor at 100% is described as 'spicy clove blossom carnation woody'. Methyl isoeugenol has been identified by chemical analysis in 18 of 91 essential oils, which have caused contact allergy/allergic contact dermatitis. Methyl isoeugenol was classified in the group of rare sensitizers, indicating that one or cases of contact allergy/allergic contact dermatitis to it have been observed. Case reports of allergic contact dermatitis from methyl isoeugenol have not been found. In 6 patients with positive patch tests to methyl isoeugenol, there were no co-reactions to isoeugenol. Methyl isoeugenol was present in 13 products in a concentration range of 64.9-1755.0 ppm, mean of 442.3 ppm. While searching for causative ingredients of pigmented cosmetic dermatitis in Japan in the 1970s, both patients with ordinary cosmetic dermatitis and women with pigmented cosmetic dermatitis were tested with a large number of fragrance materials.