Global concern about the potentially addictive properties of behaviors conducted on the Internet and the related public health and societal consequences is growing, sharpened into focus (and accelerated) by the COVID-19 pandemic. Around 7% of the world’s population show signs of problematic use of the Internet (PUI), also termed Internet addiction, and young people such as adolescents may be at greatest risk. Following high-profile deaths related to negative effects of online social media use (e.g. that of Molly Russell in the UK [1]), opinion leaders and the public in general are pressing for action to protect children and young people from online harms (https://www.bing.com/news/search?q=Online+Safety+Bill&qpvt=online+safety+bill&FORM=EWRE).

In response to the call for greater clinical recognition of concerns related to online behaviors, the World Health Organization, in the recent Eleventh Revision of the International Classification of Diseases (ICD-11), introduced an updated Section of Disorders due to Substance Use or Addictive Behaviors that includes two diagnoses with online specifiers, gambling disorder and gaming disorder, and a residual category in which other forms of potentially addictive Internet use that are less well researched, such as compulsive shopping or buying and problematic use of social media, may be diagnosed [2]. In addition, a new ICD-11 diagnosis of compulsive sexual behavior disorder, currently classified in the Impulse Control Disorders section, may be appropriate for individuals with problems related to online viewing of pornography.

In 2017, the European Cooperation in Science and Technology (COST) established a COST Action European Network for Problematic Internet Usage [3], a four-year multidisciplinary collaboration of experts in PUI (including neuroscientists, psychologists, clinicians, computer scientists, human rights lawyers, sociologists and experts by lived experience). Advances were made in setting the research agenda and reviewing pertinent scientific breakthroughs in the field, including those related to psychiatric classification, underlying etiology, and clinical intervention [4].

Yet, despite these advances, the scale and impact of PUI upon health and wellbeing remains a largely neglected topic of inquiry. Information and evidence on early identification and management of disorders involving PUI is also largely lacking. Globally, there are wide variations in the range and scope of regulatory and public and clinical health policies and models. As observed with other industries generating products with potential harms, such as alcohol and gambling, there is an expectation that increased regulation or perceived market penetration in some jurisdictions will result in greater attention on low-income and middle-income countries as the next opportunity for commercial development, with associated concerns regarding potential exploitation [4]. Therefore, global solutions for PUI are needed.

Against this background, this special issue builds upon and extends the work of the COST Action. The issue provides expert updates on the critical scientific advances in PUI that we believe form the basis for much-needed evidence-based recommendations to advance health policy and improve health practice at a global level in the ‘postpandemic’ landscape.

The work falls into multiple subsections: