New psychoactive substances in the prison setting: health implications and challenges for healthcare

People deprived of liberty show a significantly higher prevalence of psychoactive substance use compared with the general population, which is associated with increased morbidity and mortality and a higher risk of clinical complications during imprisonment. Although traditional drugs remain the most commonly consumed substances in prisons, recent years have seen a diversification of the drug market with the emergence of new psychoactive substances, characterized by high potency, rapid chemical modification, unpredictable toxicity and major difficulties in analytical detection. The introduction and use of these substances in prison settings represent a challenge for public health and clinical practice due to the limited sensitivity of routine screening tests, the variety of concealment and trafficking methods, and the absence of specific antidotes for most of these substances. The aim of this work is to review and update the scientific evidence available up to 2025 on their use in prison settings, integrating information from national and international sources. The main groups detected in recent years, their clinical effects, associated intoxication syndromes, current recommendations for clinical management, as well as limitations of detection systems and emerging routes of introduction into prisons are analysed.