Contact allergy to cosmetics: testing with patients' own products

In a 2-year period, 1527 patients with contact dermatitis were investigated in the patch-test clinic. In 531 patients, allergy to cosmetics was suspec ted from the history and they were tested with their own cosmetic products. 40 (7.5%) (of the 531 patients) had 1 or more positive reactions, 82 (15.4 %) had doubtfully positive reaction(s) and 31 (5.8%) had irritant reaction( s). Skin-can products were tested most frequently and were also found to ca use most positive, doubtfully positive and irritant reactions. 80% of the p atients with positive reactions to their own products had no history of con tact dermatitis prior to the presenting attack, and in 92.5% of the cases, the positive reaction was considered relevant or partly relevant. In patien ts with a positive reaction, ingredients that could be responsible were fou nd in 60% of the cases by testing with the European standard series and a s eries of common cosmetic ingredients. Fragrance mix and formaldehyde were f ound to be the ingredients most often responsible and were significantly mo re frequent in patients with positive reactions to their own products, comp ared to a control group of eczema patients also seen in the patch-test clin ic.