Childhood Asthma, a chronic condition, is frequently reported. International guidelines for children and young people (CYP) support using Leukotriene receptor antagonists (LTRAs) however they are often debated for their potential adverse effects. Thus a study investigated the reported frequency of adverse drug reactions (ADRs) from LTRAs in CYP with asthma by exploring Embase, MEDLINE, PubMed and CINAHL. Eligible studies underwent assessment for the risk of bias or quality of data.6853 patients were listed who received an LTRA. 13 papers were sorted who reviewed the ADRs related to montelukast, and 1 each to pranlukast and unspecified LTRAs. Language standardization identified 48 ADRs, 20 of which were psychiatric disorders. In all studies, common ADRs were ‘anxiety’, ‘sleep disorders’ and ‘mood disorders’. The frequency of ADRs could be estimated in 7 of the 8 studies. After standardization, 14 ‘common’ and ‘uncommon’ ADRs were noted. Agitation/hyperactivity/irritability/nervousness, aggression and headache were described to be the common ADRs. Similar patterns were observed in case reports that showed 46 different ADRs experienced by 8 patients.Thus LTRAs can produce a spectrum of ADRs in CYP, especially gastrointestinal and neuropsychiatric disorders. Hence CYP with asthma must be monitored carefully to assess and manage ADRs and to terminate the treatment when clinically stable.Dixon EG, Rugg-Gunn CE, Sellick V, et al. Adverse drug reactions of leukotriene receptor antagonists in children with asthma: a systematic review. BMJ Paediatrics Open 2021;5:e001206. doi: 10.1136/bmjpo-2021-001206