Background. The new psychoactive drugs (NPD) are those that represent a danger to public health and are not prohibited by conventions on international narcotics. The concept also includes new contexts and new routes of consumption as well as novel ways of distribution, notably Internet. The risks associated with NPD consumption are largely unknown to users and to health care providers. Objective. To integrate the existing evidence regarding the main NPD in terms of description, epidemiology, psychopharmacology, medical complications and psychoactive effects. Method. To review relevant and updated clinical information on NPD obtained from specialized books and indexed scientific journals (PubMed/Medline, Google Scholar, Scopus), as well as official documents edited by international organizations dedicated to the epidemiologic analysis of drug abuse and Internet websites and forums managed by psychoactive substance users. Results. Aspects of clinical and pharmacological interest are described comprehensively, together with epidemiological data and risks associated to the consumption of the most relevant NPD: synthetic cannabinoids, synthetic cathinones, NBOMe series, indoleamines, piperazines, hallucinogenic mushrooms (Psilocybe SP.), synthetic opioids, plant products (khat, kratom, Salvia divinorum, ayahuasca) and dissociative anesthetics. Discussion and conclusion. The emergence of the NPD is a phenomenon on the rise with important consequences for public health. Learning about new trends in drug consumption and its potential risks should be essential for the medical professional. New research is needed in order to understand the phenomenon of the NPD and its pharmacological, clinical and legal implications.