ABSTRACT
This chapter discusses the contact allergy and allergic contact dermatitis is the side effect of topical drugs most frequently observed by dermatologists and reported in literature and is the main subject. The prevalence of allergic contact dermatitis to topical drugs in patients patch tested by dermatologists for suspected contact dermatitis is estimated at about 15%. In epidemiological studies, these patients often have very high prevalences of positive patch tests with multi-sensitization to active drugs, excipients of topical drugs and unrelated allergens. Photoallergic contact dermatitis to topical drugs, formerly frequent with topical phenothiazines, is currently rare with the notable exception of some non-steroidal anti-inflammatory drugs such as ketoprofen, piroxicam, diclofenac and benzydamine. Systemic contact dermatitis, its manifestations and topical drugs that have caused it are discussed below. Systemic contact dermatitis is a condition that occurs when an individual sensitized to a contact allergen is exposed to that same allergen or a cross-reacting molecule through a systemic route.
