To limit the spread of the coronavirus infection COVID-19, which has received the status of a pandemic, a lockdown was temporarily introduced. In conditions of isolation, children and adolescents suffering from attention deficit hyperactivity disorder (ADHD) were faced with forced changes in their daily routine in the form of a transition to distance learning, a decrease in physical activity, an increase in time in front of TV screens/computer monitors/tablets, etc. The review provides current evidence on the associations between social restrictions caused by the COVID-19 pandemic and behavioral problems in children and adolescents with ADHD. The main factors that can influence the severity of the disease in children and adolescents are analyzed. Particular attention is paid to the role of parental behavior and its influence on the manifestations of ADHD in children in isolation. The results of numerous observations and online surveys of relatives and children suffering from ADHD have demonstrated a multidirectional trajectory of the disease depending on numerous factors, including relationships with parents and immediate family. Despite the end of the COVID-19 pandemic, the effects of isolation during critical periods of childhood have the potential to increase the burden of mental illness. Treatment of children and adolescents with ADHD during the COVID-19 pandemic should be pathogenetic, taking into account the main symptoms of the disease. When choosing pharmacotherapy, priority should be given to drugs with verified effectiveness and a reliable safety profile.