ABSTRACT
After a first volume in the series Monographs in Contact Allergy on ‘Non-fragrance allergens in cosmetics’ (1), a second on ‘Fragrances and essential oils’ (2) and a third on ‘Topical drugs’ (pharmaceuticals) (3), the subject ‘systemic drugs’ may seem a logical choice for Volume 4. In fact, however, it is not, as there are major differences between the contents of this book and the previous volumes. The haptens/allergens presented previously are all applied to the skin or mucous membranes, where they can induce sensitization and, upon renewed or prolonged contact, elicit allergic contact dermatitis. Contact allergy to these substances is frequent. Indeed, in an estimated 10-15% of all patients with allergic contact dermatitis seen by dermatologists, topical drugs are the cause (iatrogenic allergic contact dermatitis) (3, 4, 5, 6). Fragrance allergy is even more important: in the general adult population, up to 4.5% may be allergic to fragrance materials, and in consecutive patients patch tested for suspected contact dermatitis, the frequency may reach 20 to 25% (7).
