No, Simply Touching Fentanyl Can't Kill You

An anesthesiologist explains fentanyl 101.


George Anderson used fentanyl patches to alleviate pain caused by multiple myeloma. Photo credit: Gerry Melendez/TNS/Newscom

For all the ink American media outlets have spilled covering the increase in fentanyl-related overdose deaths, few of the stories I've read explain how fentanyl works or why it's so deadly.

As a result, journalists have created the impression that fentanyl is a magically awful drug. In that sense, it has a lot in common with PCP, methamphetamine, and crack cocaine. "Using [crack] even once," ABC's Peter Jennings declared in a 1989 episode of World News Tonight, "can make a person crave cocaine for as long as they live." If there's an equally believable-but-untrue claim about fentanyl, it's that simply touching the stuff can kill you.

I thought it might be useful for other reporters, and people who are simply concerned and/or curious about fentanyl, to figure out which oft-reported claims are true, partially true, or flat out wrong. So I got in touch with the Stanford anesthesiologist Steven Shafer, an expert in the pharmacology of pain medicine. I've edited our exchange for length and clarity.

Q: How do street-level doses of fentanyl—which seem to range from less than a milligram to a few milligrams—compare to surgical doses?

A: A milligram of fentanyl is a huge dose, one that would be fatal. For surgery we typically use doses of 0.1 milligram (100 micrograms). In terms of street drugs, the high potency has a very practical implication: The stuff is difficult to measure. There would be no obvious difference to a user given a packet of fentanyl-laced heroin if it had a very small amount of fentanyl, or a guaranteed fatal dose of fentanyl. The user would need to trust whomever weighed out the fentanyl used to lace the heroin.

Q: What makes illicitly used fentanyl deadlier than other opioids?

A: Fentanyl effect peaks at 5 minutes after an intravenous injection. The fast onset is more likely to be fatal than a slow onset, because the body doesn't have time to build up carbon dioxide. With a slow onset opioid (e.g., morphine), breathing slows gradually as the drug starts to act, and carbon dioxide rises. As carbon dioxide rises, it drives ventilation, offsetting (somewhat) the effects of the morphine on breathing. With the rapid onset of fentanyl, there is little time for carbon dioxide to raise before there is full effect of the fentanyl on depressing breathing. That will result in more lethality for the same maximal opioid drug effect.

Q: What do we mean when we say fentanyl is "x times more potent" than other opioids?

A: Potency is usually given for opioids by the amount (by weight) of drug required to achieve a particular drug effect. For example, one could use the "Minimal Effective Analgesic Dose," basically the lowest dose of a drug that produces some amount of pain relief. Potency can also be discussed in terms of tissue concentration, what is the plasma concentration of drug that produces a particular effect.

Because of differences in pharmacokinetics (drug uptake, distribution, and metabolism), differences in dose and differences in concentration may vary several-fold. The rate of blood brain equilibration also makes a difference. Fentanyl effect peaks at five minutes after an intravenous injection, and it's washed out by 90 minutes. Because it has slow blood-brain equilibration, morphine effect is quite modest at five minutes, but peaks at 90 minutes. Thus, it's tricky to talk about one drug being X-fold more potent than the next, because it depends on exactly when you measure drug effect. At five minutes? At 90 minutes? You will get very different answers for relative potency depending on exactly when you make your measurements.

If one says that fentanyl is 50 times stronger than drug X, you can't tell from the statement if that means that it takes 1/50th of the dose, or if it requires 1/50th of the concentration. Thus, the key concept is that fentanyl is gobs more potent than drug X, so you need a very small fraction of fentanyl compared to the other drug to get a big effect. It's not more scientific than that, because so many details affect how the potency is calculated and compared.

Q: Is it possible to develop a tolerance to fentanyl? Are users at higher risk of overdose due to lack of tolerance if they inadvertently take fentanyl mixed into a non-opioid formulation?

A: Tolerance develops to all opioids. Fentanyl is no better, or worse, than others. However, tolerance is shared: Tolerance to heroin will make the addict also tolerant to fentanyl. Tolerance also occurs with benzodiazepines. If an addict who is tolerant to valium mixes it with a "normal" amount of fentanyl, and then takes a whopping dose of valium, they may overdose from the fentanyl.

Q: EMTs have reported needing larger doses of naloxone to reverse fentanyl overdoses. Does that sound correct?

A: It depends on the dose. Fentanyl is displaced from the mu opioid receptor just like morphine, oxycodone, or any other opioid. Naloxone will work just fine. However, because fentanyl is so potent, the person mixing it into heroin might make a 10-fold dose error. In that case, it will take 10 times the amount of naloxone. So there's nothing magic about fentanyl, other than that it is so potent that it's hard to get the dose right when you are using crude scales to mix it together.

Q: Is fentanyl dangerous to touch, as several law enforcement agencies have reported?

A: No, fentanyl is not dangerous to touch. Transdermal fentanyl patches deliver fentanyl across the skin, but they require special absorption enhancers because the skin is an excellent barrier to fentanyl (and all other opioids). However, it is readily absorbed through mucus membranes, so snorted, rubbed in the mouth, or swallowed are all effective ways of administering fentanyl.

Q: Does fentanyl produce a better high than other opioids?

A: It isn't fundamentally different from other opioids, like heroin, morphine, or oxycodone. In terms of drug effect, an opioid is an opioid is an opioid. They all bind at the mu opioid receptor, and they all have the same fundamental properties. So fentanyl isn't going to give addicts a better high. Addicts like the "rush" of the fast onset, so they might prefer the fentanyl rush to the onset of a slower opioid like morphine. However, the net opioid effect will be the same.

Q: In terms of what various public health agencies are doing globally to reduce overdose rates, what kind of strategies do you think are worth trying in the U.S.?

A: This is a very complex question! There are several parts to the answer. First, we need to develop better strategies of managing pain. A lot of addiction starts with opioids given for pain management. This is because there is almost no pain that cannot be managed effectively for a short time by opioids. In other words, opioids are very effective short-term analgesics. There seems to be nothing else that can replace them. We need to find ways to limit opioid use for chronic pain, except at the end of life, because they cause addiction and lead to dependence. The other problem is that we need better ways to treat psychological pain. Psychological pain is handled by the same brain pathways that handle physical pain. That's why we use the same word, "pain," for both. Opioids are effective for psychological pain as well, but they are a terrible choice.

Q: Are there any harm reduction strategies that might reduce fentanyl overdose rates specifically? I know some facilities in Canada offer free reagent testing, but I've also seen it argued that reagent testing is not an effective way to identify fentanyl in a mixture.

A: That would work, as long as it is sufficiently sensitive. One could readily make over the counter fentanyl detection kits so that addicts could identify if their concoction has been laced with fentanyl. That would likely be a good idea.

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  1. Speaking of anesthesiologists, Mike Riggs once had open heart surgery without anasthesia. He didn’t even need surgery. He just wanted to see his own beating heart. He then wrestled a pound of fentanyl out of an alligator’s mouth, while getting stitched back up.

    1. Ahem. Why are you assuming he had someone else perform the surgery?

      1. I see nothing there that indicates anyone else (other than an alligator) was involved.

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  2. I hear they’re putting Fentanyl in pixie sticks so kids will snort it and die.

    1. I hear every piece of hard candy given out this Halloween is going to be laced with Fentanyl. It’s a partnership between Big Pharma and Big Sugar.

      1. Big Phuger? Big Sharma? Pig Barma? Pig Buger? Some of those are pretty interesting.

  3. “over the counter fentanyl detection kits”
    Best idea all day.

  4. Hey Mike, Rather than talking about how its cool to shoot up fentanyl maybe you guys should be talking about how fucking Dear Leader is going to get us into a nuclear war because he fucking can’t shut his fucking mouth at the UN.

    Dear North Korea, Dear Leader lives in Washington DC or on a golf course in Florida– not California. Can you direct your retaliatory response there, please? Trust me, we here in California collectively feel the same way as you guys do about him.

    1. Reason is known specifically for its sparse coverage of Trump and Kim Jong Un.

    2. Who told all the Lefties that today was the day to start slobbering on Kim’s knob?

    3. Don’t worry his missiles can only reach Alaska.

    4. Hey commie faggot, sucking Kim’s cock worked well for the last 25 years, didn’t it? Trump isn’t a weak little pussy like your pal Obama. It’s about time someone put that little butterball tyrant Kim in his place.

      Oh, and rather than attempting to think, which is NOT your strong suit, maybe you should just shut up and listen to your betters (libertarians).

  5. Great interview, Mike. I can’t think of any topic that has a greater informational disconnect between professionals and laypeople than drug use, but stuff like this helps.

    1. I think a lot of laypeople only pretend to believe the drug alarmists’ stories just so it isn’t obvious that they’re well aware of what it’s like to use drugs.

  6. “Using [crack] even once,” ABC’s Peter Jennings declared in a 1989 episode of World News Tonight, “can make a person crave cocaine for as long as they live.”

    I’ve noticed the same thing about brownies.

    1. Were those brownies with or without hashish oil?

  7. Dr. Shafer nails everything cold until the second to last question. A lot of addiction DOES NOT START with opioids given for pain management. There is ample evidence in the literature that addiction arising from pain management is rare, ranging from 0.5% to 10%, much more likely to be at the lower end. The fentanyl OD crisis was started people *abusing* drugs, especially OxyContin. When the abuse-resistant formula came out in 2010 its use dropped sharply and heroin ODs rose likewise. When fentanyl hit the country in force in 2014 it partially/largely replaced heroin and you can now see the results. Do not try to blame what is going on now on patients or their doctors. It is from people who chose to get high in the absence of pain who were the driving force. Yes, we certainly do need better pain drugs and strategies, but withholding opioids from people who need them will help no one and hurt many.

    1. It would be unusual for addiction to start with opioids given to otherwise normal people for pain management.

      But that distinction is largely based upon the definition of addiction. Which is largely behavioral

      Dependence, on the other hand, being wholly physiologic, develops rapidly with the routine use of any opioid.

      Both doctors and their poorly informed patients (sometimes in both cases misled) have done a poor job of managing this entirely foreseeable consequence that sometime does lead to addiction.

      Personally I think we need to take the model that is used in addiction management/maintenance programs – monitored therapy with special concern for maintaining the highest degree of social function (e.g. don’t OD, keep your job, keep your spouse, stay out of the legal system, etc.) and apply it to opioid use in the treatment of chronic pain. Too often the prescriber only treats the pain, and is oblivious to pretty much everything else going on with the patient. That narrow focus is largely how we got to where we are now.

  8. People in chronic pain chronically take pain relievers.

    14 Year Veteran Undercover Cop Exposes Truth About The Drug War: “I Used To Believe I Was Doing Good”

    “When I went into policing I thought addicts had made the mistake of trying drugs and had no willpower to stop. Actually, problematic drug users ? or at least all the ones I knew ? were self medicating. Most of the heroin users I knew were self-medicating for childhood trauma, whether physical or sexual.

    The doctor may be a wiz at anesthesia. He is ignorant when it comes to “addiction”.

  9. “This is because there is almost no pain that cannot be managed effectively for a short time by opioids.”

    Yes, but only if you append that sentence with a couple paragraphs of caveats. Key ones involving the limits of the words “almost,” “managed,” and “short.” Ignore the very critical meanings of those words and you can be headed for troubles.

  10. I have to disagree with one point as far the high opioids are not all the same. Oxycodone has a different effect that hydrocone as does codeine.

    1. Indeed. And they don’t affect people equally.

  11. Voice to text sucks balls on iPhones. Let me clarify , in my experience, the feel different and people get different effect based on bill logical differences. For som, opioids cause drowsiness, other experience incred enerngy and insomnia.

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  13. Why are you trying to disrupt the fentanyl hysteria with facts?

  14. All these opioids are for pain, right?

    We as humans have been around a long time without these drugs. Maybe more doctors should just advise their patients to “walk it off.”

    1. Which came first, poppies or people?

  15. I touched Fentanyl. And I died. Who’s stupid now?

  16. Great interview, Mike, Really thanks

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