Veni, vidi, vici: The appearance and dominance of new psychoactive substances among new participants at the largest needle exchange program in Hungary between 2006 and 2014

• Since 2010 a number of NPS appeared and disappeared depending on their legal status.
• Heroin and amphetamine combined diminished from 99% until 2010 to 17% in 2014.
• The number of older and female clients have increased due to a number of factors.
• Over 80% of PWIDs use NPS and injecting NPS is linked to increased injecting risks.
• Harm reduction services should be more available to avoid HIV and HCV epidemics.

BackgroundThere has been an almost exponential growth in the number of new psychoactive substances (NPS) on the drug markets in Europe during the past decade. While most users of NPS use them by routes other than injecting, percutaneous use of NPS is associated with very frequent injecting episodes and paraphernalia sharing.MethodsWe assessed to what extent new clients between 2006 and 2014 (N = 3680) at Blue Point, Hungary's largest needle exchange program, exhibited a shift during these years in the drugs they primarily injected.ResultsUntil 2010, 99% of clients injected either heroin or amphetamines. After 2010, however, there was a “replacement chain” of new substances, with one appearing and disappearing after the other: between 2010 and 2014, NPS under five names appeared and gained dominant prevalence (from 0% to 80%), and gradually replaced first the two “traditional” drugs amphetamine and heroin (which diminished to 17% together in 2014) and later each other. We also saw an increase in the proportion of female and older clients.ConclusionsWhile our findings are restricted to injected NPS, they suggest that NPS affect the vast majority of the population of people who inject drugs not only in terms of drug use patterns, but maybe also in terms of demographics. Given that over 80% of people who inject drugs use NPS and injecting NPS is associated with increased injecting risks, harm reduction services should be made more available to avoid an epidemic of blood-borne infections.