I have worked at the National Institute of Psychiatry in Mexico in the northern border of Mexico with injecting drug user population in places of high vulnerbility. My main fields of interests are the consumption of heroin, crystal meth and the adulterance with fentanyl.

The epicenter of fentanyl use in Mexico has been located in Tijuana and Mexicali, two cities on the U.S. border characterized by drug use. In recent years, these cities have seen the largest seizures of fentanyl in the country as well as the exponential growth of its use and that of other adulterants such as xylazine. In Mexico, the consequences of the modification of the drug supply, which has shifted from the use of heroin to fentanyl with xylazine, have been devastating for the most vulnerable communities on the northern border, Persons Who Inject Drugs (PWID) among whom overdose mortality has the greatest impact. In recent years, the Ramón de la Fuente Muñiz National Institute of Psychiatry with Verter, Prevencasa and Programa Compañeros NGOs, the National Autonomous University of Mexico, the Tijuana Institute of Technology, the Center for Research and Advanced Studies and the Autonomous University of Baja California have monitored changes in the drug market, health consequences and the lived experience of people in this region. In 2018 PWID mainly used black tar heroin, known as chiva in Mexican Spanish, without knowing it was heroin. In 2020 for the first time, we found heroin adulterated with fentanyl through the drug checking technique. In 2023 we detected the presence of xylazine in the 20% of 300 samples of heroin analyzed using mass spectroscopy, together with a rapid increase in fentanyl. These results revealed a complex, challenging reality: fentanyl consumption spread rapidly along the northern border and showed how xylazine contributed to this health crisis shared with the United States. It is urgently required to address the perceived needs of PWID demanding access to a dignified life which could represent a hopeful sign for the reconstruction of peace processes in a region affected by insecurity, violence, and for people’s suffering.