Purpose of review: The multiple drug hypersensitivity syndrome (MDH) is a distinct clinical entity, different from cross-reactivity and flare-up reactions. Following its initial description in 1989 by Sullivan et al., several authors have addressed the issues surrounding this peculiar form of drug hypersensitivity. Whether this syndrome is single or can be further classified in several entities is still a matter of debate.
Recent findings: Case reports, case series or studies involving large populations on MDH are few. The use of this term in the literature is heterogeneous, and the definitions variable. Given the major advances in the study of drug hypersensitivities in general, and ongoing research regarding severe cutaneous adverse reactions in particular, careful study of the subgroup of patients with demonstrated immunological basis of MDH has enabled the generation of possible pathogenetic hypotheses. Together with the studies (despite their limitations) to estimate the prevalence of this syndrome in adult and paediatric patients these emerging data need confirmation through larger studies with well defined populations.
Summary: Bringing together the experience of groups involved in the field of drug allergy should help to move knowledge regarding this peculiar form of drug hypersensitivity forward.