ABSTRACT
Already more than half a century ago it was discovered that some drugs that had caused an exanthema could induce a positive patch test reaction, pointing at the existence of delayed-type (type IV) hypersensitivity to it. In the last 25 years, the relationship between cutaneous adverse drug reactions and systemic drugs and this form of hypersensitivity (which causes allergic contact dermatitis when the allergens [haptens] are applied to the skin and is termed ‘contact allergy’ then) has been extensively investigated. It was found that certain drug eruptions are frequently associated with delayed-type hypersensitivity, of which the macular and maculopapular (morbilliform) exanthematous eruptions are by far the most frequent.
