Contact dermatitis from antioxidants.

In a search for contact sensitivity to antioxidants we patch tested consecutive patients referred with eczematous dermatitis. Six cases of allergic contact sensitivity to nordihydroguairetic acid (NDGA) were observed. Three had been sensitized by one brand of cream containing 0.1% NDGA, in three patients the source of sensitization could not be traced. In four patients we found positive patch tests to butylated hydroxyanisole and/or to butylated hydroxytoluene. In two cases the positive patch tests were relevant, since both patients remained asymptomatic when antioxidants were avoided in food. They both had acute flares of vesicular eczema on the fingers after oral administration of small amounts. Gallate esters and Vitamin E (d,l-alpha-tocopherol) each gave one unexplained positive patch test. The present data suggest that further search for hidden sensitizers in topical medicaments and cosmetics is warranted. A declaration of all ingredients in industrial products should be placed on the label.