The opioid crisis just keeps getting worse, in part because new types of drugs keep finding their way onto the streets. Fentanyl, heroin’s synthetic cousin, is among the worst offenders.

It’s deadly because it’s so much stronger than heroin, as shown by the photograph above, which was taken at the New Hampshire State Police Forensic Laboratory. On the left is a lethal dose of heroin, equivalent to about 30 milligrams; on the right is a 3-milligram dose of fentanyl, enough to kill an average-sized adult male.

Fentanyl, according to the Centers for Disease Control and Prevention, is up to 100 times more potent than morphine and many times that of heroin.


Drugs users generally don’t know when their heroin is laced with fentanyl, so when they inject their usual quantity of heroin, they can inadvertently take a deadly dose of the substance. In addition, while dealers try to include fentanyl to improve potency, their measuring equipment usually isn’t fine-tuned enough to ensure they stay below the levels that could cause users to overdose. Plus, the fentanyl sold on the street is almost always made in a clandestine lab; it is less pure than the pharmaceutical version and thus its effect on the body can be more unpredictable.

Heroin and fentanyl look identical, and with drugs purchased on the street, “you don’t know what you’re taking,” Tim Pifer, the director of the New Hampshire State Police Forensic Laboratory, told STAT in an interview. “You’re injecting yourself with a loaded gun.”

New Hampshire, like the rest of New England, has been particularly hard hit by the opioid epidemic. The state saw a total of 439 drug overdoses in 2015; most were related to opioids, and about 70 percent of these opioid-related deaths involved fentanyl. The state has seen 200 deadly opioid overdoses this year so far, said Pifer.

Fentanyl was originally used as an anesthetic. Then doctors realized how effective it was at relieving pain in small quantities and started using it for that purpose. In the hands of trained professionals — and with laboratory-grade equipment — fentanyl actually has a pretty wide therapeutic index, or range within which the drug is both effective and safe.

The difference in strength between heroin and fentanyl arises from differences in their chemical structures. The chemicals in both bind to the mu opioid receptor in the brain. But fentanyl gets there faster than morphine — the almost-instantaneous byproduct when the body breaks down heroin — because it more easily passes through the fat that is plentiful in the brain. Fentanyl also hugs the receptor so tightly that a tiny amount is enough to start the molecular chain of events that instigates opioids’ effects on the body.


Sign up for our Morning Rounds newsletter

Please enter a valid email address.

This tighter affinity for the opioid receptor also means more naloxone — or Narcan — may be needed to combat a fentanyl overdose than a heroin overdose.

“In a fentanyl overdose, you may not be able to totally revive the person with the Narcan dose you have,” said Scott Lukas, director of the Behavioral Psychopharmacology Research Laboratory at McLean Hospital in Belmont, Mass. “Naloxone easily knocks morphine off of the receptor, but does that less so to fentanyl.”

Matt Ganem, a former addict, explains the excruciating process of opioid withdrawal. Alex Hogan/STAT

Leave a Comment

Please enter your name.
Please enter a comment.

  • I am on day 10 of taking my 50 mcgs of Fentanyl patch. I was on for 6 years it was HELL! I seized, spent 6 days in the hospital and they could not control it. Do not do at home do inpatient. I still am not alright.

    • Or don’t do it unless you’re dying. It’s a dog eat dog world people. Don’t listen to anyone you don’t trust.

  • “…The chemicals in both bind to the mu opioid receptor in the brain. But fentanyl gets there faster than morphine — the almost-instantaneously— because it more easily passes through the fat that is plentiful in the brain. Fentanyl also hugs the receptor so tightly that a tiny amount is enough to start the molecular chain of events that instigates opioids’ effects on the body…”

    This explains why we read about so many more cars and trucks drifting off the road and colliding into sides of houses or worse yet crossing lanes and colliding head on into an on coming vehicle. The impaired driver has overdosed on opioids and is fast asleep behind the wheel while his out of control car travels at deadly speed. This opioid impaired, comatose driver is operating a lethal weapon, committing at least the crime of involuntary manslaughter and law enforcement and the courts must bring the perpetrator and his supplier to justice.

  • In the early 90’s the drug companies sent Vicodin samples in a little foil package to dental offices to give to patients. Problem is the staff would take and use them and got addicted after about five days of taking only 2-3 pills a day. I don’t know what some of them did when they quit the job.

  • I hate illegal drugs – especially since I was in the Army in 69-70-71. LSD was rampant at Ft Gordon Georgia. Heroin was everywhere in VN. The behavior of the users was disgusting especially the nearly comatose and drooling H addicts.
    Legalize drugs? Very, very stupid. Don’t put that shite in your body.

    • Im not attacking what you believe, but i disagree. When I was in school, cannabis was easier to get than cigs or alcohol. I say decriminalize it all, and create a safe alternative, for people who have the desire to do such things.
      There are many countries that do it, and it appears to work out the opposite of what you would probably think. As long as people avoid equality,there will be a constant culture war happening

  • Years ago, back in 2007 I tried to explain to a Physician why a prescribed Fentanly Patch was dangerous. Thanks to the Lobbying efforts of Pharma, and the AMA, Physicians chose to remain willfully ignorant. They refused to take Continuing Ed in Pain Management or Opiate Addiction. They let people with Chronic Pain suffer and die, after they stopped prescribing, and refused to treat them. They refused to treat people with addiction too.
    There is nothing new here, the unscientific and ill advised reaction to the Opioid Epidemic created this. Even now people are dying and they are still putting more restrictive legislation on pain patients, and legitimate pain Physicians. It is easier than dealing with the Corporations who undermined the law in search of profit. Facts and Data are just inconvenient, it was more profitable to have the media still mislead the public.
    There are shortages now of pain medications for surgery, burns and trauma, because none of the reaction was thought out.
    This is the logical extension of unregulated for profit healthcare. There were no surprises here, this was all calculated. They are not going after the cause of this, instead they are going to double down on the ignorance and stupidity.
    Maybe if there are any Scientists left in a few years to do objective research, they will come to the conclusion that this was Genocide. After all the British, used opium, to get a foothold in China. They used to teach that in History Classes.
    We live in dangerous times folks, where the profiteers make policy. This is even more dark and dangerous than we know. The US used to have Laws and regulations on marketing pharmaceuticals, our politicians took money to do away with the Laws. The for profit healthcare system did not even collect clear data on the dead, by design. At the same time our media refused to cover or explained away, the activities of the corporations that profited. They promoted a “Free Market” deceiving the public at every turn. Even now the speeches and committees are deceptive. We can;t expect a bunch of industry insiders who paid off our politicians to come up with a rational response.

    • I was in Viet Nam when I saw the movie MASH, and was inspired by its theme song. I knew that what was given to “Painless” was probably a licorice jelly bean. I’ve had the same problem as “Painless” for the past 20 years. So what?

      As the 6th Mass Extinction’s events become more obvious so has the poisoning of the planet’s food and water resources. The Collapse of global populations from starvation, caused by our failure to invent an effective response to the 90,000+ manmade chemicals floating about in our spaceship’s biosphere, was originally expected sometime between 2030 and 2050. In the 40 Year Update of Limits To Growth, their research confirmed that the tipping point was in 1975, and that it would become obvious NLT 2024, aka, any time now.

      Can you imagine the pain and suffering of watching family members dying of starvation? Don’t have to go very far to see it happening here in the U$. There being no such option as a “Black Mariah,” how likely is it to find a lethal dose of fentanyl?

      I suspect that choice is the only option for those of us who remember: “Solve The Problem; Failure is not an option,” and know that we are not able to adapt/evolve an effective survival strategy for the 6th Mass Extinction. That’s why it is called a mass extinction. Unlike an on/off switch, a dimmer switch with multiple short circuits should be expected.

      We all know that we are not getting out of here alive, but becoming extinct boils down to sooner rather than later. I’d rather not make the choice of a Twin Towers leapers, ie, splat vs a BBQ. Bridges, ropes, hoses, guns, Sepuku, kool-aid, cops or X, knowing that my transition to whatever is really next need not be painful. In fact, I can imagine a “wake” whilst still alive, shared with friends before climbing into a casket to be put into a canoe and set ablaze into the receding tide has a romantic atmosphere about it, don’t you think?

Sign up for our Daily Recap newsletter

A roundup of STAT’s top stories of the day in science and medicine

Privacy Policy