Rosacea and contact allergy to cosmetics and topical medicaments--retrospective analysis of multicentre surveillance data 1995-2002.

The role of contact allergy in rosacea has rarely been investigated. In this retrospective study, 361 out of 76,697 patients tested and documented by the Information Network of Departments of Dermatology between 1995 and 2002 had rosacea. Patch tests included standard series and constituents of cosmetics and topical medicaments. 118/361 had additionally been patch tested with their own cosmetics/medicaments. Positive reactions occurred to nickel (II) sulfate in 9.3%, fragrance mix in 8.8%, thimerosal in 6.9%, Myroxylon pereirae resin in 5.9%, potassium dichromate in 4.6% and propolis in 2.8%. Whereas rosacea patients had a significantly higher risk of contact allergy to propolis compared to the remaining patients, in an age- and sex-adjusted analysis, contact allergy to nickel was significantly less frequent in this group. For Lyral, the risk was elevated, albeit not significantly. Only 2/329 patients were positive to neomycin sulfate and 1/100 to gentamicin sulfate, among the panel of (topical) antibiotics tested. Among 118 patients tested with their own products, 3 were tested to metronidazole, 1 reacting positively. Irritant or doubtful patch test reactions were provoked by various substances (vehicles, oxidants and preservatives of various creams), which might also be clinically important, considering the heightened sensitivity of rosaceous skin.