The worldwide increase of life expectancy, changes in immunological capacity, comorbidities and polytherapy are responsible for the increasing prevalence of geriatric drug related allergic skin diseases. In the elderly other factors contribute to the onset of these phenomena, such as changes in the structure of the skin and mucous tissues. The integrity of the epithelial barrier in old people is compromised by the loss of its constituents, that predisposes to alterations of the hydrolipidic film with dryness, xerosis and pruritus. Also at the skin level are frequently found abnormal immunological reactions towards new antigens and a chronic inflammatory state that predisposes to a response oriented towards the Th2 cytokinic pattern, allowing allergens to penetrate into tissues. Nevertheless, in the elderly drug related allergic disorders, in particular at the skin level, are often underdiagnosed and difficult to treat.
Among the IgE mediated cases, urticaria and angioedema are frequent. However, there are also cell-mediated mechanisms; in particular delayed type reactions to drugs often arise in the elderly for the reiterate use of topical medications (anesthetic, antibiotic and anti-inflammatory creams).
A detailed anamnestic history is essential to establish the causal link between an adverse drug reaction and the specific drug. Moreover, in some cases it is necessary the specific knowledge of the histological picture.