Montreal public health warns about new synthetic opioid linked to overdoses
Posted November 26, 2025 8:24 am.
Last Updated November 26, 2025 1:33 pm.
Montreal public health officials are warning about cychlorphine, a synthetic opioid recently detected in the city’s street drug supply and linked to several overdoses.
The substance has been found in fentanyl powders and counterfeit oxycodone and hydromorphone tablets, but current drug-checking tools cannot detect it.
With little data available on cychlorphine’s toxicity, officials urge drug users to be cautious and emphasize that naloxone should be used in any suspected overdose.
“Cychlorphine was detected in substances found at the scene of two deaths believed to be due to overdose,” said Dr. Alexandra Larocque, emergency medicine specialist and toxicologist at Quebec Poison Control Centre and Montreal Public Health. “We have not yet received confirmation at this time that cychlorphine is directly involved in these deaths. The exact number of non-fatal cychlorphine-related overdoses is unknown, but we have at least 2 confirmed cases,” added Dr. Larocque.
“Naloxone is an antidote that blocks the effects of opioids on the brain and therefore reverses toxic effects, including decreased or stopped breathing and the effect on consciousness,” added Dr. Larocque.
Symptoms include slowed or stopped breathing, gurgling sounds, unresponsiveness, blue lips or nails, and pinpoint pupils, all of which can quickly lead to cardiorespiratory arrest.
“This substance is indeed different from medetomidine, for which a call for vigilance was issued in September,” said Dr. Larocque. “Cychlorphine is an opioid (same large family as heroin, fentanyl, hydromorphone, etc.).”
Authorities advise calling 911 immediately in an overdose situation and are asking clinicians and frontline workers to reinforce prevention efforts and alert users to the risk of unknowingly consuming cychlorphine.
If drug users do consume cychlorphine, notify someone and stay in contact with a resource like the National Overdose Response Service (NORS) 1-888-688-6677, Remote Service for Overdose Prevention (RSOP) 1-800-265-2626, option 2.
