Ackermann L, Aalto-Korte K, Jolanki R, Alanko K. Occupational allergic contact dermatitis from cinnamon including one case from airborne exposure. Contact Dermatitis. 2009;60(2):96-99. doi:10.1111/j.1600-0536.2008.01486.x

Reviewed by Jalal Maghfour, Alina Goldenberg MD

Cinnamon is derived from the bark of cinnamon trees Cinnamomum Zeylanicum or Cinnamomum Cassia. Cinnamon has a versatile function and is widely used in food, pharmaceutical and cosmetic industries.

Allergic contact dermatitis (ACD) to cinnamon is very rare but has been reported by several authors across the literature. Cinnamal aldehyde is what makes cinnamon an allergenic compound. It also is what gives the rich odor and flavor to cinnamon. Upon contact with the skin, cinnamal aldehyde can act as an allergen. This binding results in an immune complex reaction that triggers the inflammatory cascade resulting in ACD.

Herein this synopsis we provide an overview of a study describing six patients who developed ACD due to a sensitization to cinnamon.

Of the six patients, three developed ACD primarily on the hands, where they had direct contact with cinnamon powder, contained in flour/rye. One patient developed ACD on the neck and face area presumably caused by airborne exposure to cinnamon in a working environment.

For diagnosis of any ACD, a detailed history and patch testing are required in order to identify the offending agent. However, spices are well known to be irritating in patch testing, which may result in high rate of false-positives.  Therefore, diluting series for patch testing is recommended for accurate diagnosis. Additionally, cinnamon is not commonly tested via patch testing, rather cinnamic aldehyde and cinnamal, strong sensitizers found in fragrances, are tested which can cross-react.   Therefore, patients with confirmed patch testing due to fragrance mix containing eugenol, cinnamal and cinnamyl alcohol should be counseled on the possible cross-reactivity with cinnamon. 

In summary, cinnamon is a very rare allergen, but has been reported to induce ACD. Patch testing is the gold standard diagnostic tool to elucidate an underlying cinnamon sensitivity.

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