Cutaneous drug hypersensitivity: developments and controversies

Cutaneous drug hypersensitivity reactions (CDHRs) are a complicated area with multiple clinical manifestations and differential diagnoses, requiring differentiated diagnostic measurements and optimized therapeutic management.Disseminated CDHRs to classical drugs can be classified by a simple algorithm, whereas chemotherapeuticals or biopharmaceuticals may show drug-specific and atypical clinical presentations. Controversies in drug hypersensitivity diagnosis exist about the benefit and accuracy of in-vitro tests. Although skin tests are the best means of detecting sensitization to drugs, methods have not been sufficiently standardized. The necessity for skin tests before performing drug provocation test (DPT) and of prolonged DPTs is discussed in selected patients. If a suspicion has been documented, β-lactam allergy should be excluded. The standard allergy diagnosis is done by an allergist. In case of urgent need because of an infection and low risk according to history, faster delabeling pathways have been developed. There is weak evidence that patients with mastocytosis may have a slightly increased risk of developing immediate-type drug hypersensitivity; however, if considerations are taken, drugs do not have to be withheld for this patient group. There is particular need for improved diagnostic measurements in patients with drug-induced severe cutaneous adverse reactions (SCARs), both identifying the offending drug and detecting individuals at risk. Further challenges encompass appropriate treatments during the acute as well as chronic phase of SCARs.Recent literature has contributed to our understanding of clinical manifestations and existing controversies and future needs in this area.