Occupational allergic contact dermatitis from cinnamon including one case from airborne exposure

Background: The bark of the cinnamon tree is used as a spice; its flavour is from an essential oil containing mainly cinnamal. Objective: To report new cases of occupational allergic contact dermatitis (ACD) from cinnamon and a novel case of airborne cinnamon contact allergy. Methods: We examined the patient material of two dermatological clinics in Helsinki to find cinnamon contact allergic patients and review their clinical records. Results: We found six patients with delayed contact allergy to cinnamon. In four patients, cinnamon was the main cause of occupational ACD. Three of them had dermatitis on their hands and one patient on the face and neck. In the latter case, the exposure was shown to be airborne. In addition, the fifth patient was occupationally sensitized to cinnamon, but it was not the main cause of his hand dermatitis. In the sixth patient, cinnamon allergy was considered to derive from cross-allergy to fragrances. Five of the patients reacted to cinnamal separately and in fragrance mix I. None of the six patients had immediate-type cinnamon allergy. Conclusions: Occupational contact allergy to cinnamon is rare but needs to be considered in workers handling foods. Cinnamal is possibly the main allergen in cinnamon.