Which contact allergens are important in central Europe?

Contact allergy occurs when the skin comes into contact with small molecules called haptens, causing the skin to become ‘sensitised’. This means that if the skin comes into contact with the same hapten (or allergen) again, it may develop inflammation called allergic contact dermatitis, which is a type of eczema. When a patient is thought to suffer from allergic contact dermatitis, ‘patch testing’ is used by dermatologists to find out what the substance causing the reaction might be. This is done by applying a screening baseline (standard) series of possible haptens, together with other substances that are suspected to be relevant after discussion with the patient about possible triggers. Because of changing environmental exposure (e.g. a change of ingredients in cosmetics or toiletries), the frequency of different haptens can vary with time, and continued surveillance is needed to keep up to date with these trends. This study from Germany provides an update of the current prevalence of contact allergy. It describes patch test results, clinical details and demographics of patients presenting to departments in Germany, Austria and Switzerland. Over the period 2007‐2018, 125,436 patients were tested to the German baseline series. There were no significant changes in the commonest allergens, including nickel and fragrance mix. However, other allergens showed variation over the period. A major example is a dramatic rise in positive results to a preservative called methylchloroisothiazolinone/methylisothiazolinone. However, following a European Union ban of its use in cosmetics that are left on the skin, and a limit to its concentration in cosmetics that are washed off the skin, the prevalence of allergy to it has decreased more recently. Other allergens, such as propolis (bee glue) continue to be prevalent, and the authors recommend its inclusion in the baseline series of other countries. Linked Article: Uter et al. Br J Dermatol 2020; 183: 857–865.