Medetomidine, also known as “dex,” is an animal sedative used by veterinarians that has been increasingly found mixed with illegal opioid drugs like fentanyl. It’s similar to another animal tranquilizer called xylazine, which is also known as “tranq.”
Scientists don’t know much about medetomidine. What is known is that people who sell drugs are mixing it more often with illegal opioids. This makes these already dangerous drugs even more harmful to people who use them.[1]
In Toronto, medetomidine has been found in about 11% of the fentanyl tested. In the United States, medetomidine has shown up in drug samples and in tests of people who use illegal opioids in at least 18 states and Washington, D.C.
Philadelphia experienced a serious problem with medetomidine beginning in 2024. In just three days, 160 people ended up in the hospital after using drugs that contained it. Some people have even died from using drugs mixed with medetomidine.
Looking at cases across the country, researchers have found more deaths linked to medetomidine in fentanyl. This problem is especially bad in large cities.[2]
One of the dangers with medetomidine is that most hospital lab tests don’t show the substance. Asa result, healthcare providers may treat a person’s opioid use without realizing that they also need to take added measures to treat medetomidine. Unlike xylazine, there are no testing strips yet that can quickly detect this substance. Because testing is lacking it makes it more difficult to fight this growing health crisis.[3]
Scientists don’t know much about how medetomidine affects people. They aren’t sure if mixing this substance with opioids makes these drugs’ effects more intense or last longer. They also don’t know if it’s more likely to cause serious health problems or death. More research is needed to understand these dangers.[4]
Medetomidine’s sedative effects can look a lot like what happens with opioids like fentanyl, heroin and pain pills. It can cause drowsiness, slow breathing, and decreased heart rate. Sometimes it can be difficult to tell if a person is just nodding off or overdosing on an opioid that has been laced with medetomidine. Even when someone does identify an overdose, medetomidine can make it harder to reverse the effects.
This is why it’s important to call 911 right away if someone is found unconscious, even before giving naloxone. When medetomidine is mixed with opioids, you might need more than one dose of naloxone to reverse an overdose.
Very often, a person might not breathe properly even after naloxone is given because of the medetomidine. That’s why rescue breathing seems a standard practice to reverse an overdose when medetomidine is involved. To do this, having a 1-way valve CPR mask is recommended. For this reason, people who might need to give naloxone should also learn how to use these special CPR masks. After giving the first dose of naloxone, they should use the mask until the person starts breathing on their own or until 2 minutes have passed.[5]
There may be instances when a person cannot be stabilized and will need to get care in the hospital. If breathing continues to be irregular, the person may need to be intubated to restore natural breathing.[6] Also, hospitals are administering a medication, dexmedetomidine, which seems to help with withdrawal symptoms.[7]
It is also important to keep the person hydrated with hydration tablets and water. Having snacks at hand is a good idea to help regulate blood sugar levels. Experts also recommend keeping people warm even when the temperature is high.
When someone has been using opioids laced with medetomidine, treating the opioid use disorder becomes more difficult. Experts warn of severe withdrawal symptoms. Within a couple of hours after taking medications that help relieve opioid withdrawal symptoms, they may still experience high blood pressure, hypertension, tachycardia, tremors, and chills. These symptoms are due to the effects of stopping the medetomidine.[8]
This is similar to what happens with xylazine.
Because of these withdrawal symptoms, people might be tempted to go back to using the drug mix that contains medetomidine, rather than sticking with their treatment. This makes recovery from opioid addiction even more challenging
Even though scientists still don’t know much about medetomidine, there are steps your loved one can take to stay safer if they use illegally obtained opioids: