Adequate implementation of evidence-based pharmacotherapies is an obvious precondition for their effectiveness in real-life settings. Indeed, ‘Drugs do not work in patients who do not take them’, as the well-known quote by C. Everett Koop, US Surgeon General, says (Everett Koop, 1985). Unfortunately, despite more than half a century of dedicated research, corrective and awareness-raising activities, medication adherence still remains far from perfect. Twenty years ago, the World Health Organization released its seminal report on adherence (World Health Organization, 2003), which popularised the memorable number of as many as 50% of patients deviating from their prescribed treatment. Even if it may be assumed that these statistics seriously simplify the problem of non-adherence, there are also good reasons to believe that this proportion was not overestimated. What is worse, current statistics of non-adherence are not much different (Foley et al., 2021). An analysis of the milestones of medication adherence research and practice (Figure 1) proves that patients’ deviations from prescribed treatment are as old as the medicine itself. Hippocrates, the father of medicine, was the first one to make a note of what we now call non-adherence. This phenomenon has since not only caused frustration for thousands of practitioners, but has also been the object of interest for thousands of researchers. As a result, currently conducted searches of scientific literature databases using medication adherence terms return over 100,000 records. What can we learn from that bulk of publications?

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