Background Attention‐deficit/hyperactivity disorder (ADHD) is often associated with other neurodevelopmental disorders (NDs) and with risky behaviors and adverse health outcomes, including injuries. Treatment with ADHD medication has been associated with reduced risk of injuries. However, it is unknown whether the association is present in individuals with co‐occurring NDs. The aim of the present study was to estimate the association between ADHD medication use and unintentional injuries in Sweden in children and adolescents with ADHD, including those with co‐occurring NDs.

Methods Using a linkage of several national registers via the unique personal identification number, we identified individuals with a diagnosis of ADHD and of other NDs, including autism spectrum disorder, intellectual disability, communication disorders, learning disorders and motor disorders. The primary outcome was unintentional injuries. Secondary outcome was traumatic brain injury (TBI). Individuals were followed from January 1st 2006 or their 5th birthday or the date of the first unintentional injury, whichever came last, to December 31st 2013 or their 18th birthday or death, whichever came first. We compared the rate of injuries during periods on‐treatment with the rate of injuries during periods off‐treatment within the same individual using stratified Cox regression to calculate hazard ratio (HR) with 95% confidence intervals (CIs).

Results For children and adolescents with ADHD (N = 9,421) the rate of any unintentional injuries (HR = 0.85; 95% CI = 0.78–0.92) and TBIs (HR = 0.27; 95% CIs = 0.20–0.38) during medicated periods was lower than during non‐medicated periods. Similar results were found among individuals with co‐occurring NDs (N = 2,986), for unintentional injuries (HR = 0.88; 95% CI = 0.77–1.01) and for TBIs (HR = 0.27; 95% CI = 0.16–0.44).