Background: Melaleuca oil (tea tree oil) is the essential oil distilled from the leaves of Melaleuca alternifolia Cheel. Tea tree oil is popular for treating various cutaneous maladies.
Objective: Our purpose was to determine which constituent compounds of Melaleuca oil are responsible for allergic contact eczema in seven patients who became sensitized.
Methods: The seven patients were patch tested with Finn Chambers to a 1% solution (vol/vol) of melaleuca oil and 1% solutions (vol/vol) of 11 constituent compounds.
Results: Of seven patients reactive to the 1% melaleuca oil solution, six patients also reacted to limonene, five to alpha-terpinene and aromadendrene, 2 to terpinen-4-ol, and one each to p-cymene and alpha-phellandrene. d-Carvone, an autooxidative derivative of limonene, caused no reactions among the seven patients.
Conclusion: d-Limonene was the most common allergen causing allergic contact eczema in our patients. Clinicians are likely to see more contact eczema caused by the increasing use of this popular nostrum.