Most people have heard of fentanyl, the synthetic opioid that’s 50 times stronger than heroin and is largely responsible for more than 150 overdose deaths each day, per the Centers for Disease Control and Prevention (CDC).
But now a new drug has emerged that makes fentanyl even more dangerous.
The Drug Enforcement Agency (DEA) has issued a public safety alert about xylazine — also known by its street name "Tranq" — which is increasingly being mixed with fentanyl.
"Xylazine is making the deadliest drug threat our country has ever faced, fentanyl, even deadlier," said Anne Milgram, administrator, in the DEA’s statement.
"The DEA has seized xylazine and fentanyl mixtures in 48 of 50 states. The DEA Laboratory System is reporting that in 2022, approximately 23% of fentanyl powder and 7% of fentanyl pills seized by the DEA contained xylazine."
Here’s what you need to know about this dangerous drug.
Xylazine was originally approved in 1972 for use by veterinarians as a sedative, pain reliever and/or muscle relaxer, according to the DEA.
It’s commonly used on animals large and small to calm them before exams and surgery. It can also be used as a pain reliever or local anesthetic.
Rob Louie, executive vice president of clinical services at RemedyOne in New York, points out that xylazine is extremely potent.
"About 3ccs [0.10 fl. oz.] will put a 1,000-pound cow on the ground, while the same amount would relax a horse enough to stand there and be shoed," he told Fox News Digital in an email.
"Just three-tenths of a cc — a very small amount — will fully sedate a human and possibly cause death."
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David I. Deyhimy M.D., an addiction medicine and anesthesiology physician in San Clemente, California, compared xylazine to a medication used for anesthesia in humans called dexmedetomidine, which is intended to keep people asleep during surgery and other medical procedures.
"Because it is not studied in humans, there is no known safe dose," he said in an interview with Fox News Digital.
While often mixed with opioids, xylazine is not an opioid itself.
For this reason, the National Institute on Drug Abuse says overdoses can’t be addressed with naloxone (more commonly known by brand names Narcan and Kloxxado).
However, when xylazine is mixed with fentanyl, naloxone may reverse the fentanyl if given in a high enough dose, said Dr. Deyhimy.
"When a person using is unresponsive and with signs of respiratory depression or no breathing, naloxone should always be used," the doctor said.
"You don't know what is causing respiratory depression, but if an opioid like fentanyl is involved, naloxone will be useful and may help restore breathing."
He added, "A person who has taken xylazine and fentanyl may start breathing again after naloxone — but might not wake up or be responsive after administration."
Dr. Deyhimy noted that naloxone won’t hurt people who are not experiencing an opioid overdose — but may help those who are, even if mixed with other drugs not reversed by naloxone.
Xylazine is often added to other illicit substances — most commonly fentanyl, but also heroin, cocaine, methadone, prescription opioids and others, said the CDC. That mixing is done to achieve a longer high or to increase the weight of the drug in order to charge a higher price for it.
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"When mixed with other drugs like fentanyl, xylazine potentiates certain effects, such as sedation and respiratory depression, making the combination of the drugs more dangerous than either one alone," Dr. Deyhimy warned.
The doctor said there is no way to determine whether xylazine has been mixed with other drugs unless it’s tested in a lab.
"Like fentanyl and other synthetic drugs, you can't predictably know if it is present and in what amount," he added.
Xylazine is sold legally in liquid form to veterinarians through pharmaceutical suppliers.
However, the DEA states that it can also be easily purchased online from Chinese suppliers in liquid or powder form for as cheap as $6 per kilogram.
"The legally marketed form for veterinarians is a solution that is intended to be injected, but those abusing the drug could potentially inject, snort, swallow or inhale it," said Dr. Louie.
Xylazine is a nervous system depressant.
The drug acts on alpha 2 receptors in the brain to cause sedation, muscle relaxation and respiratory depression, depending on the dose, said Dr. Deyhimy.
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"It can also cause low blood pressure, increase or slow heart rate, cause abnormal heart rhythm — and can lead to coma and death," he warned.
Additionally, Dr. Deyhimy said that people can develop tolerance to and severe withdrawal from xylazine, which may cause chest pain and seizures.
"Xylazine is not safe for use in humans and may result in serious and life-threatening side effects that appear to be similar to those commonly associated with opioid use, making it difficult to distinguish opioid overdoses from xylazine exposure," the FDA stated in a press release on its website in November 2022.
The National Institute on Drug Abuse states that xylazine overdose deaths are rising, with the greatest impact in the northeastern United States.
In Pennsylvania, xylazine was involved in more than a quarter of all overdose deaths in 2020, up from just 2% in 2015.
In Maryland, 19% of drug overdose deaths involved xylazine in 2021.
The drug was linked to 10% of Connecticut overdose deaths in 2020.
Xylazine has been dubbed the "zombie drug" due to its side effect of causing the rotting of human tissue.
"When xylazine is injected, it can cause serious skin wounds, infections and tissue necrosis [death]," Dr. Deyhimy told Fox News Digital.
"Some people have had such severe wounds that they have required limb amputations."
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The FDA has warned that these wounds can also develop in other areas of the body outside the injection site.
With the growing prevalence of dangerous additives like fentanyl and xylazine, doctors warn that any illicit drug could potentially be life-threatening.
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"Powerful synthetic drugs like fentanyl and xylazine have contaminated the entire illicit drug supply," said Dr. Deyhimy.
"Counterfeit pills that look identical to the pharmaceutical originals routinely cause overdose and death."
He refers to these as poisonings rather than overdoses — because victims have no idea what they are actually ingesting.
"These drugs are so powerful that death can occur in minutes after administration," he warned.
