Opioid Overdose Management

In the past few years, a new public health crisis has been identified. Deaths from the direct effect of opioid drugs are escalating.

February 27, 2024

The Ontario Poison Centre is aware of pharmaceutically active substance contamination in the illicit drug supply in Ontario and Manitoba. Of note, in the recent past, xylazine, dexmedetomidine, and metomidine have been detected in the supply. These substances are all alpha2 agonists. They act at receptors in the Central Nervous System to decrease sympathetic outflow. The resulting symptoms include depressed level of awareness, mild hypotension and bradycardia. As these substances are often found in the opioid supply, the expected respiratory depression, and other symptoms already known to occur from opioids are likely to be exacerbated.

The opioid toxidrome can be reversed by using naloxone. As opioid withdrawal can be precipitated by the use of naloxone, it is suggested that doses of naloxone for the depressed patient suspected of having been exposed to illicit drug supply, start low and be escalated slowly if respiratory rate and oxygen saturation are not improved. Classically, usual opioids are very responsive to naloxone. Some of the designer opioids (carfentanyl and others) may require higher doses. The maximum dose to be given should be no more than 10-12 mg. Should there be an incomplete response or should the patient not respond to the maximum dose, then there is no further benefit to additional naloxone. Should a patient have a good response but become depressed again, the wakeup dose can be repeated or an infusion started.

The alpha2 agonists do NOT respond to naloxone. Should the patient have inadequate response to naloxone, then the usual supportive care must be maintained until these medications are metabolized & eliminated. This may include intubation, oxygenation, ventilation, and blood pressure support beyond intravenous fluids.

Flumazenil is never indicated. The alpha2 agonists do NOT interact at the GABA receptors. Many illicit drugs are also contaminated with benzodiazepines. Chronic use of illicit opioids equals chronic use of benzodiazepines to the unsuspecting consumer. These patients are also now benzodiazepine dependent. Flumazenil will precipitate acute benzodiazepine withdrawal increasing the likelihood that these patients will seize.

Call the Ontario Poison Centre for specific care for your patient.
Margaret Thompson, MD, FRCPC
Medical Director, Ontario & Manitoba Poison Centres


Across Canada, deaths from the direct effect of opioid drugs have escalated over the last several years. Many new potent opioids, including fentanyl and its analogues, are available on the streets. These may be used as substitutes for heroin and cocaine, or found as contaminants of these drugs. Even those who use opioids regularly may not be tolerant to these relatively potent opioids, resulting in unexpected overdoses. The opioid known as carfentanil is an example of a fentanyl analogue.

Opioids typically cause a person to have a depressed level of consciousness, a decreased respiratory rate and small or pinpoint, pupils. With increasing intoxication, respirations can stop, and further injury from hypoxia, including coma and cardiac arrest, can occur.

Health-care Professionals

Most pharmaceutical opioids, heroin and fentanyl, should respond to usual doses of naloxone. The desired response to naloxone should be establishment of adequate respirations, to have an O2Sat > 90% and a pCO2 < 45 mmHg. The patient does not need to be fully awake and alert. With naloxone dosing health-care providers have always been taught to "start low and go slow" to prevent acute opioid withdrawal. Although uncomfortable, opioid withdrawal is generally not life threatening.

MPC has guidelines for pre-hospital and hospital opioid resuscitation here.

General Public

Treatment for the opioid overdosed person currently consists of supportive care and the antidote naloxone. Naloxone is available in Manitoba from “Take-Home Naloxone” distribution sites which offer free take-home naloxone kits and training to individuals who are either at risk of an opioid overdose, or a friend or family member of a person at risk of an opioid overdose. In addition, anyone can purchase a naloxone kit at a community/retail pharmacy or store that has naloxone kits for sale.

MPC has guidelines for the lay rescuer here.


Opioid Facts and Myths


Fentanyl and its analogues can be absorbed through mucous membranes.  
Many users have snorted the drugs and have become overdose victims.  In the medical literature, there was a single report of a veterinarian mistakenly splashing himself in the eye with carfentanil which required a dose of an antidote to resuscitate him.

There is some evidence that carfentanil was one of the incapacitating agents used to stop the Chechen takeover of the Dubrovka theatre in 2002. In this instance, carfentanil was delivered as a gas into the theatre and would have been absorbed through the lungs. In the media, there are two videos of police officers, who inhaled carfentanil powder developing symptoms.

Fentanyl and analogues are absorbed from the GI tract.
These drugs, as contaminants, are often taken by mouth in pill form. Absorption might be slightly slower but the overdose effect is the same once absorbed.

Carfentanil is potent enough to sedate an elephant. Special protection must be worn at all times.
Large animal veterinarians do use these potent fentanyl analogues to sedate or anaesthetize animals. Individuals protect themselves by wearing gloves, long sleeves and eye protection when handling the drugs. Border security personnel and post office staff, when opening suspicious packages, are using similar protection but also open these exhibits under a fume hood.

Suspected drug labs are particularly dangerous.
When entering a drug lab where illicit opioids are being manufactured, the powders of fentanyl or its analogues may be free to be inhaled. The US Drug Enforcement Administration recommends that individuals entering suspected drug lab and pill pressing facilities are appropriately protected using Hazmat gear. Field testing substances is NOT recommended as equipment will NOT have many of the new analogues in the library so will give false positive or negative results. Police wear a mask to double seal an exhibit.


Fentanyl powder and its analogues can poison you if touched.
The lay press and even some government publications have sensationalized the issue to state that fentanyl powder and/or its analogues can poison you if touched. This is not the case. Inadvertent dermal exposure to the powder will not cause toxicity. If however, powdered drug remains on the skin, (e.g. on your hand) and subsequent oral contact is made (e.g. hand goes in mouth), absorption might occur through mucous membranes.

Rescuers may succumb to opioid overdose when helping victims.
Although very small doses of fentanyl and its analogues can be dangerous, there are no reports of rescuers succumbing to opioid overdoses when helping victims. There are no reports of peers, EMS workers or hospital staff getting ill by providing basic lifesaving care to these victims. Universal precautions should be followed as per usual.