Overdose deaths from carfentanil — a dangerous drug that is stronger than fentanyl — are on the rise, according to a recent report from the Centers for Disease Control and Prevention (CDC).
The US has been struggling with an opioid crisis for decades, with thousands of overdose deaths each year. But a report published on December 5 in the CDC Morbidity and Mortality Weekly Report showed that opioid overdose deaths are finally on the decline. The percentage of deaths caused by illicitly manufactured fentanyl also declined slightly.
But the report’s authors warned that there appears to be a “resurgence” of a synthetic opioid called carfentanil – with deaths caused by the drug increasing sevenfold – which could “undermine this progress” the country sees otherwise.
The report found that carfentanil deaths increased by more than 720% in the first half of 2023 compared to the first half of 2024.
These deaths have been reported in 37 states, meaning the drug is relatively common in the US. Eight states – New York, Maryland, Florida, Illinois, Michigan, Ohio, West Virginia and Kentucky – each reported over 20 carfentanil-related deaths.
Carfentanil is not as well known to the public as fentanyl, and carfentanil overdose deaths are still considered “rare,” according to the report. The drug has been linked to 513 overdose deaths between January 2021 and June 2024.
But the extreme spike in cases is worrying, experts said Health. Here’s what you need to know about carfentanil, how it compares to other dangerous drugs, and whether it could affect the opioid crisis in the U.S. in general.
Carfentanil is a synthetic opioid traditionally used as a tranquilizer for elephants and other large animals, Diane Calello, MDexecutive medical director of the New Jersey Poison Information and Education System and a professor at Rutgers New Jersey Medical School, said Health.
The drug was first created in the 1970s and is sold under the name Wildnil.
Opioids, in small doses, can relieve pain and induce relaxation, Kalelo explained. However, unlike fentanyl and oxycodone, “carfentanil is not used to control pain in humans,” she said.
Carfentanil is 100 times stronger than fentanyl and 10,000 times stronger than morphine, so “even a small amount can cause overdose and death,” he said. Havre Jalal, MD, PhDCanada Research Chair in Health Economics and Associate Professor of Epidemiology and Public Health at the University of Ottawa.
“Carfentanil, like fentanyl, crosses the blood-brain barrier and binds to mu-opioid receptors in the brain, which are responsible for pain relief and euphoria,” Jalal said. Health. “However, carfentanil binds much more strongly than natural endorphins or other opioids, making it significantly more dangerous.”
When someone is exposed to carfentanil, they will usually have trouble breathing and thinking, fall into a coma and experience “respiratory arrest,” Calello said. In other words, the drug can cause people to stop breathing.
The body can start to have a reaction to carfentanil after being exposed to just one microgram – a minimal amount.
The drug naloxone (also known as Narcan) can quickly reverse an opioid overdose and can counteract a carfentanil overdose, Jalal said. However, these overdoses can be difficult to treat.
“Due to the extreme potency of the drug, multiple doses may be required in rapid succession, reducing the likelihood of a successful reversal,” he explained.
Exposure is also challenging to treat because of how quickly carfentanil works in the body, Calello said.
“Patients can die before they can receive treatment,” she explained.
Carfentanil “does not have an approved medical use in humans,” but has entered the illegal drug trade, Jalal said. However, unlike other drugs, “most ingestions are probably accidental,” he explained.
“It’s a contaminant or an adulterant in the drug supply, meaning the person using it doesn’t expect to be exposed to it,” Calello said.
People who overdose on carfentanil are usually exposed to the drug when they take fentanyl, she added. According to a CDC report, from July 2023 to June 2024, nearly 87% of people who died from carfentanil also had illegally manufactured fentanyl in their system.
This differs the current trend from documented outbreaks of carfentanil overdose deaths in 2016 and 2017, the report’s authors added.
Nearly a decade ago, states such as Florida and Ohio recorded hundreds of carfentanil-related deaths, although only a quarter of them also involved fentanyl. But now carfentanil overdoses are being seen in dozens of states and appear to be occurring with fentanyl use, which is cause for greater concern.
“The potential mixing of carfentanil into fentanyl products as an adulterant raises concerns that its presence may be unknown to drug users, reminiscent of how fentanyl was first introduced as an adulterant of heroin,” the report said.
It’s not entirely clear whether carfentanil deaths will continue to rise in the coming months or years, but experts are concerned.
In addition to the fact that people may be adding carfentanil to other illicit drugs, the prevalence of these overdose deaths is concerning, Jalal said.
“During the 2016-2017 carfentanil outbreak, precursor chemicals from China fueled a localized increase in overdose deaths,” he said. “After China regulated fentanyl in 2018, carfentanil-related deaths declined. The current epidemic appears to be more widespread, affecting 37 states, posing greater challenges to controlling supply and mitigating its impact on the opioid crisis.
Still, it’s important to note that for now, exposure to carfentanil is “much less common than fentanyl,” although the former is more likely to cause an overdose, Calello noted.
However, if the situation changes and “carfentanil becomes a more common component of illegal drugs, the number of opioid overdose deaths will increase and some of the progress that has been made will be reversed,” she said.