Severe cutaneous adverse reactions due to inappropriate medication use

Summary Background The proportion of severe cutaneous adverse reactions (SCARs) that could be avoided if medication use was consistent with good medical practice is unknown. Objectives To estimate the proportion of SCARs related to inappropriate medication use. Methods We carried out a retrospective study of all validated SCARs collected in a French registry between 2003 and 2016. For each case, all plausible drugs suspected of inducing SCARs (i.e. not just the drug regarded as ‘the most probable’) were considered with regard to (i) prescription for an inappropriate indication, (ii) unintentional rechallenge despite a previous allergy to the drug or (iii) self‐medication with prescription medicines. Results In total, 602 cases were included in the analyses. Antibiotics, anticonvulsants and allopurinol were the drugs most frequently involved, accounting for more than 50% of all cases. All suspected medications were considered to have been appropriately used for 417 of the 602 individuals included in the study population [69·3%, 95% confidence interval (CI) 65·6–73·0] and inappropriately used for 144 individuals (23·9%, 95% CI 20·5–27·3). These inappropriate uses were due mainly to prescriptions for an inappropriate indication (65·8%, 95% CI 58·4–73·2) or unintentional rechallenge (20·9%, 95% CI 14·6–27·2). Allopurinol and co‐trimoxazole were the drugs most frequently involved in inappropriate indications. Antibiotics were the largest group involved in unintentional rechallenge. Nonsteroidal anti‐inflammatory drugs, available on prescription, were most frequently involved in inappropriate self‐medication. Conclusions Our results underline the need for respecting the appropriate indication for drugs in order to reduce the incidence of SCARs. Reducing unintentional rechallenge also seems to be a necessary preventive measure. What's already known about this topic? Severe cutaneous adverse reactions (SCARs) carry high morbidity and mortality. Evidence is limited regarding the proportion of SCARs that could be avoided if medication prescriptions were consistent with good medical practice. What does this study add? This cohort study found that one‐quarter of SCARs could be avoided if indications for medication use were consistent with current good medical practice. Adherence to guidelines regarding the use of allopurinol and co‐trimoxazole is a decisive factor in preventing SCARs. Linked Comment: Walsh and Creamer. Br J Dermatol 2018; 179:242–243. Plain language s