Allergic contact dermatitis from potassium sorbate and sorbic acid in topical pharmaceuticals and medical devices.

BACKGROUND The preservatives sorbic acid (SA) and potassium sorbate (PS) are considered rare skin sensitizers. PS-containing products always contain SA to a certain extent, and positivity to PS may reflect sensitization to SA. Their optimal patch test conditions are unknown. OBJECTIVES To report on the outcome of testing with SA and PS in various concentrations and/or vehicles. PATIENTS AND METHODS Seventeen patients with allergic contact dermatitis from PS/SA-containing topical pharmaceuticals and medical devices were patch tested to SA 2% and 5% pet., SA 1%, 2%, 3%, 5%. eth., and/or SA 2% aq., whereas PS was patch tested at 5% pet. and/or 5% aq. RESULTS Only one patient, not tested to the ethanol preparations, presented with a (doubtful) positive reaction to SA 2% pet., while this remained negative in 13 patients who reacted to SA 2% eth. The preparations containing SA 5% pet., 1%, 3%, and 5% eth., and SA 2% aq. had little or no additional value. PS 5% pet. performed better than 5% aq., and always mirrored SA sensitization. CONCLUSIONS Sensitization to SA and PS is probably underestimated. SA 2% eth. and PS 5% pet. are preferred for patch testing, and patients sensitized to SA should avoid PS-containing products. This article is protected by copyright. All rights reserved.