Compound tincture of benzoin: a common contact allergen?

The results of patch testing to compound tincture of benzoin in 477 patients performed at the Contact Dermatitis Clinic at the Skin and Cancer Foundation in Melbourne during 1999 are presented. There have been fewer than 30 reported cases of contact allergy from compound tincture of benzoin, and none in the last decade. Our results showed 45 out of the 477 patients had a positive reaction to compound tincture of benzoin, which was the third most common allergen in our series. Of these 45 patients, 14 had strong positive reactions, but only two definitely recalled exposure to compound tincture of benzoin and these were clinically relevant. Twenty-eight of these patients had cross-reactions to similar allergens (fragrance mix, balsam of Peru, colophony and tea tree oil). Of the 14 patients with a strong positive reaction to compound tincture of benzoin, 11 had at least one other positive cross-reaction to the above allergens. This may explain the high frequency of reaction to compound tincture of benzoin found in our study.