Emergence of synthetic drugs in South America: insights from Brazil, Chile, and Colombia.

Abstract

The illicit drug landscape in South America is going through a major shift. The appearance of Tusi (or "pink cocaine"), a mixture often containing ketamine and MDMA, along with the growing presence of synthetic opioids like fentanyl and nitazenes, signals a new chapter in the region's drug use, which has been traditionally dominated by alcohol, cannabis, and cocaine. Drawing on data on seizures, forensic analyses, warning systems, and surveys from Brazil, Chile, and Colombia, this perspective highlights three movements of the drug supply: non-prescribed and synthetic opioids, ketamine, and Tusi. We also elaborate on their unique public health challenges. Brazil and Chile have seen an increase in non-prescribed opioid use, some of them diverted from healthcare, accompanied by seizures of illicit fentanyl and the discovery of nitazene production in Brazil in May 2025. Colombia, while historically experiencing low opioid use, has documented fentanyl analogs in ketamine and MDMA/Ecstasy samples, mixed with various other contaminants, thus increasing risks among people who use them. Concurrently, ketamine and Tusi use are expanding rapidly across all three countries, particularly among nightclub attendees and youth with criminal-legal involvement. Tusi's unpredictable composition poses heightened overdose risks, especially in settings lacking drug-checking and overdose-prevention education and programs. Furthermore, South America has minimal opioid agonist therapy coverage, limited naloxone access, and underdeveloped harm reduction systems. The emergence of synthetic opioids, ketamine, and Tusi signals a new synthetic drug phase in South America's supply. The convergence of traditional drugs with potent new substances poses important health-related harms. Strengthening regional surveillance, toxicological monitoring, and harm reduction services are urgently needed. Coordinated international research and public health responses will be essential to prevent a drug crisis.