Overdose deaths dropped in Colorado in 2024, alongside the rest of the country, and the start of 2025 looked reasonably bright.
Then March hit.
Within Denver, 63 people died of overdoses that month, followed by 58 in April and 63 again in May – an average of two people per day, every day, for three months straight. March and May , and while experts point to changes in the drug supply as a likely culprit, no one can definitively say what happened.
Most of the people who died had both fentanyl and methamphetamine in their systems, said Dr. Sterling McLaren, chief medical examiner for the city of Denver.
Fatal overdoses also are up for the state as a whole, rising from 1,603 in 2024 to 1,813 in 2025, according to preliminary data from the .
The increase came at a time when most of the country continued to see improvement. Preliminary data shows fatal overdoses went down 15% nationwide in 2025, with the most significant drops along the coasts, .
The biggest exceptions were New Mexico, where overdose deaths rose about 21%; Arizona, 17%; and Colorado, 13%. Other states with smaller increases included North Dakota, Minnesota, South Dakota and Montana.
A chaotic supply
A shift in the form of fentanyl people use could has caused some of the overdoses, said Ally Arnaiz, overdose prevention and education program coordinator for the Denver Department of Public Health and Environment. Since fentanyl showed up in Colorado, people generally took it by smoking counterfeit pills, colloquially known as “blues,” off a piece of foil. But powder, which is easier to inject, makes up an increasing share of the supply, she said.
Without regular testing and surveys, no one can be sure if the drug supply has become more potent, or if people are using it in riskier ways, Arnaiz said. While people do overdose from smoking fentanyl, the chance is higher when injecting.
“We’re dealing with an illicit drug supply, one that does not have oversight,” she said.
than in the rest of the country, so the region might simply not be as far along the curve of reducing deaths, said Thomas Stopka, a professor of epidemiology at Tufts University School of Medicine. Other factors could include regional differences in the availability of naloxone and medication for opioid use disorder, he said.
But data from seizures does show powder fentanyl making in-roads in the Southwest, Stopka said. Powders could be more potent, and are also easier to mix with other substances, such as meth, he said.
“The fake pills may have been more predictable, to a certain extent,” he said.
Dave Olesky, special agent in charge of the Rocky Mountain division for the U.S. Drug Enforcement Administration, said the DEA also observed a shift from counterfeit pills to powder, but he sees that as a positive, since people who aren’t experienced with drugs are more willing to take a pill than to smoke or inject something.
“If somebody doesn’t take a pill that doesn’t come from the doctor, we are going to make so much progress against the fentanyl epidemic,” he said.
While cases of teenagers taking what they thought were diverted pills do happen, Denver’s 2025 data showed only 36 of the 674 people who died of drug-related causes were younger than 25, including six who were under 18. Statewide data by age isn’t yet available.
The purity of seized pills has gone down over time, though it still can vary significantly, Olesky said. People who are accustomed to a certain amount of fentanyl may be using more pills to get the desired effect, with some dying if they get a stronger-than-expected dose in the mix, he said.
Lisa Raville, executive director of the Harm Reduction Action Center in Denver, isn’t sure a shift in form is to blame. Powder fentanyl has been available to some degree for years, but with an unregulated market, people have no way of knowing if a batch is dramatically more potent than usual or contains additives that have their own risks, she said.
The Pennsylvania-based reported finding 134 relatively new substances across drug samples it tested in 2025. The sheer range of potential substances means that, even if someone uses a fentanyl test strip, .
Providers and health departments on the East Coast generally identify new contaminants in the drug supply early on. Recent additives include , a veterinary drug that can cause severe flesh wounds when injected; , another animal drug which causes a withdrawal syndrome that includes a potentially life-threatening spike in blood pressure; and more-potent synthetic opioids such as , and .
Most of the new chemicals showing up on the East Coast don’t appear to be common in Denver at this point, Arnaiz said. Drug supplies are highly variable, so each local market needs data about potency and adulterants, she said.
“The drug supply in Denver is very different from what you see in Grand Junction,” she said.
While people died from heroin overdoses, long-term users generally had a fairly accurate picture of how much they could take, Arnaiz said. The arrival of fentanyl and other additives created a more chaotic supply, where dosing is a matter of guessing, but the fear of withdrawal pushes people to take the risk, she said.
“No one wants to be dependent on a substance under these conditions,” she said.
Drug seizures are up, for good or ill
Last year, seizures of both fentanyl and methamphetamine were up about 30% in Colorado compared to 2024, said Keith Weis, executive director of the , which offers training and coordination for law enforcement in Colorado, Wyoming, Utah and Montana. No one can know the amount of drugs available on the market, but generally, higher seizures point to greater demand, he said.
The DEA had a record year for seizing fentanyl in the region, most of which starts with cartels in Mexico and moves up Interstate 25, Olesky said. One particularly notable bust was a storage unit in Douglas County holding 1.7 million counterfeit pills, plus enough powder to make about 6 million more, he said. A person not involved in the drug trade had purchased the unit’s contents without seeing them after the previous owner got arrested and stopped paying rent.
Olesky described the seizures as a major success: each pill taken off the street is no longer available for someone to misuse. But recent studies in and found short-term increases in overdoses following police drug seizures.
When someone’s usual seller gets arrested or doesn’t have product available, they find another source, which may be more potent or mixed with other substances, Stopka said. Increased law enforcement activity in an area can also make people reluctant to seek treatment or harm reduction services, he said.
“When drug seizures happen, that leads to more uncertainty in the drug supply,” he said.
How to reduce deaths?
So far, overdose deaths don’t appear to be surging in 2026, though the data is incomplete because toxicology testing can take weeks or months.
Olesky said he doesn’t think Colorado will make real progress until it provides more drug education and sends a message that substance use isn’t acceptable. The state also needs penalties for drug trafficking that are severe enough to dissuade criminals, he said.
“When you see the same things happening, the criminals are not being deterred,” he said.
Colorado increased penalties for fentanyl possession in 2022 and created the category of fentanyl distribution causing death for people who sell someone a mixture containing fentanyl, resulting in a fatal overdose. Raville believes the law has made people using drugs together less likely to call for help if someone has an overdose.
“Most people who use drugs are low-level sellers” who could face a lengthy prison term if they call for help, she said.
The city has promised that it will start distributing drug-checking machines to harm-reduction groups later this year, Raville said. Unlike fentanyl test strips, which can only detect one substance, the machines will be able to give a more holistic, real-time view of the supply, she said.
“We need to be more nimble in understanding what’s in the drug supply today,” she said.
Under the checking program, people will share a small portion of the drugs they intend to consume, Arnaiz said. Even if people still decide to use them after concerning results, they’ll still contribute to keeping others safe, she said.
“People who use drugs, despite the perception of the general community, really care about their health and the health of the community,” she said.
Denver has invested in connecting people to health care and harm reduction efforts, such as offering clean needles and naloxone, Arnaiz said. Ideally, it would be able to use funds more creatively, such as offering small rewards to people who are trying to quit stimulants – a method known as contingency management.
People get scared when they see public drug use, and compassion is running short, Arnaiz said. But relationships, along with naloxone, are some of the best tools to prevent more deaths, she said.
Raville would like to see the city set up sites where people can use the drugs they’ve purchased under supervision, meaning someone would be there to intervene if they start to overdose. But ultimately, she thinks the only thing to really stem the deaths would be a safer supply, such as medical-grade fentanyl patches and prescription amphetamines as alternatives to illicit opioids and meth.
“Alcohol isn’t legal because it’s safer. It’s safer because it’s legal,” she said.
