Montreal’s regional public health authority is warning of a sharp rise in overdoses after carfentanil, one of the most potent and dangerous opioids, was detected in fentanyl circulating in the city. The regional public health board, Centre-Sud-de-l’Île-de-Montréal (DRSP de Montréal), issued a news release Thursday, saying it has received a significant number of reports of non-fatal overdoses in recent days, all linked to the presumed consumption of fentanyl. Several cases required emergency intervention, including ambulance transport. The spike in overdoses coincides with the detection of carfentanil in multiple drug samples that appeared to be fentanyl, found in the form of differently coloured “rocks.” The sedative medetomidine, a drug used in veterinary medicine that has been circulating in Montreal’s fentanyl supply for several months, was also present in all samples tested. Carfentanil is effective in extremely small doses and is rarely detected in Montreal’s drug supply, making its current presence particularly alarming to health officials. “Reducing usual doses is recommended, since even a minimal amount of carfentanil could trigger an overdose that could lead to death,” the DRSP said in its alert. Know the signs Public health officials are urging anyone who uses drugs, or who is with someone who does, to carry naloxone and know how to use it. Naloxone is recommended when a person has difficulty breathing, is making a gurgling or snore-like sound, or is unresponsive to noise and pain. Bluish lips or fingernails and pinpoint pupils are also warning signs. These symptoms can progress rapidly to cardiorespiratory arrest. In the event of an overdose, call 911 immediately and administer naloxone if available. Hospital care may be required for naloxone administration under medical supervision or for airway management, the news release stated. Advice for users The public health board is urging street drug users to use caution regardless of how they consume substances, whether by inhalation, injection, or other methods. Specific guidance includes: Naloxone is available free of charge at pharmacies and community organizations. Under the federal Good Samaritan Drug Overdose Act, anyone who calls 911 during an overdose is protected from prosecution for simple possession.