Allergic contact dermatitis to compound tincture of benzoin.

Nineteen cases of allergic contact dermatitis to compound tincture of benzoin are described. Patch testing to individual components revealed positive reactions to all ingredients except aloe. An alternative preparation, Mastisol, was successfully used without primarily inducing allergy. It should be considered for use before benzoin because once allergy to benzoin exists, cross-reactions to Mastisol usually occur. This is probably due to the presence of a common ingredient, styrax gum.