Background: Erythema multiforme, or EM, is a hypersensitivity reaction to agents such as herpes virus, drugs or foods. Oral EM-like reactions may be induced by cinnamon. It is important for dentists to recognize this condition.
Case description: The authors report an unusual case of cinnamon-induced oral EM-like reaction in an older female patient. The disease manifested itself as chronic extensive surface ulcerations and lip swelling. The patient was treated repeatedly with topical and systemic steroids but responded to them only temporarily. The patient was cured when the offending agent--cinnamon--was eliminated from her diet.
Clinical implications: Oral EM or EM-like reactions pose a diagnostic dilemma due to their varied etiologies and clinical manifestations. Correct diagnosis is essential for effective treatment. A negative skin test does not rule out an allergic reaction to food.