Why Is Fentanyl So Deadly?

Fentanyl used to be a relatively unknown medication, but it has recently gained notoriety as a central figure in the opioid epidemic.1 This powerful synthetic opioid medication is prescribed legally in various forms under various brand names, including:2

  • Duragesic (transdermal film).
  • Sublimaze (injection).
  • Subsys (sublingual spray).
  • Actiq (lozenge).
  • Fentora (tablet).

Fentanyl is also produced and sold illegally. Fentanyl, especially illicit fentanyl and its analogues, has caused an alarming number of opioid overdose deaths in the past decade. In 2018, the U.S. saw more than 30,000 overdose deaths involving synthetic opioids other than methadone, which includes fentanyl.3 The side effects of fentanyl are similar to that of heroin.4

In 2018, the U.S. saw more than 30,000 overdose deaths involving synthetic opioids other than methadone, which includes fentanyl.

Fentanyl Side Effects

Fentanyl binds to opioid receptors in the brain to relieve pain.4 However, pain relief is not the only effect of fentanyl. Side effects of fentanyl include:4,5

  • Euphoria (extreme pleasure).
  • Drowsiness or sleepiness.
  • Confusion.
  • Headache.
  • Abdominal pain.
  • Nausea.
  • Vomiting.
  • Constipation.
  • Sedation.
  • Slowed and/or difficult breathing.
  • Loss of consciousness.

Fentanyl Potency

Fentanyl is an incredibly powerful opioid painkiller.6 It is 50-100 times more potent than morphine, and even just a small amount can cause a fatal overdose.6,7

Because it is so potent, this medication is primarily used for very severe pain, such as post-surgical pain. It is also used in the treatment of chronic pain in people who have become tolerant to other opioids.4

Frequently Asked Questions about Fentanyl

Is Fentanyl Stronger than Heroin?

Yes. Fentanyl is up to 50 times more potent than heroin.8 When it is secretly added to batches of heroin, it can result in the overdose deaths of unsuspecting users.9

Where Does Street Fentanyl Come From?

Fentanyl purchased on the street may come from prescription fentanyl that has been stolen, obtained by forged prescriptions, or diverted illegally by patients or doctors.2 However, fentanyl is now very often produced illegally. This product is referred to as illicitly manufactured fentanyl, or IMF.

According to the Centers for Disease Control and Prevention (CDC), it is IMF that is responsible for most of the fentanyl-related harm (overdose deaths, for example) in the United States.6

IMF is often added to other drugs such as heroin, cocaine or methamphetamine, often without the buyer’s knowledge.6 Fentanyl-adulterated street drugs have been responsible for many unintentional overdoses.1

How Much Fentanyl Is Lethal?

How much fentanyl is lethal may vary from person to person; however, as a general rule, it takes an extremely small amount of fentanyl to cause a deadly overdose.8 The United States Drug Enforcement Administration (DEA) produced the following image to demonstrate just what a small amount (2 milligrams, the size of 2 grains of salt) of fentanyl can be deadly in most people:

DEA fentanyl image

Credit: Drug Enforcement Administration

Symptoms and Signs of a Fentanyl Overdose

A fentanyl overdose can happen quickly. An overdose on fentanyl or other opioids can usually be identified with 3 characteristic symptoms, known as the opioid overdose triad:10,11,12

  1. Very small (pinpoint) pupils.
  2. Extreme sleepiness or unconsciousness/inability to wake.
  3. Problems breathing or stopped breathing.

Other signs of opioid overdose include:12

  • Limp body.
  • Choking sounds or gurgling.
  • Very slow or no heartbeat.
  • Cold, blue or clammy skin.

In the case of a fentanyl overdose, immediate action may save the person’s life. If you notice the signs an opioid overdose in another person, call for emergency help right away. If you have naloxone (Narcan) and know how to use it, administer it immediately. Lay the person on their side to prevent choking and stay with them until help arrives.10,12

Calling 911 Is the First Step

911 call

Naloxone administration can save the person’s life, but they still need further emergency medical care because naloxone’s effects are temporary and the person may start having life-threatening breathing problems again. Always call 911 first in the event of a suspected overdose.12

Drugs Laced with Fentanyl

Fentanyl-involved overdose deaths are not limited to those who knowingly abuse fentanyl or heroin. Often, fentanyl is found in other drugs and its presence is not known to the people who purchase and use these drugs.8  

Man cutting open heroin bag

In August of 2020, the DEA, in combination with San Diego County officials, warned of a sharp rise in overdose deaths involving illicit drugs laced with fentanyl in San Diego County. The warning included a reminder that dealers are continuing to add fentanyl to various illegal drugs, and that the combination is a “recipe for death.”8 This problem occurs not only in San Diego but all over the country.

Many people know that heroin is often laced with heroin, but they may not be aware that fentanyl has been found in numerous other drugs, including cocaine, methamphetamine and illegally produced pills, such as counterfeit oxycodone or Xanax.8,13 Part of why fentanyl is so deadly is that it shows up in so many other drugs, causing life-threatening overdose in users who have no idea they’ve taken any fentanyl at all. One such example is a 19-year old man who bought 2 counterfeit Percocet pills from a friend and died of an overdose. Fentanyl was in his system at the time of death.8 Because fentanyl may be added to a number of other substances, United States Attorney Robert Brewer compared buying street drugs to a “high stakes game of Russian roulette.”8  

The proliferation of fentanyl in the drug market has made it an incredibly dangerous time to be struggling with drug abuse or addiction. At Recovery First, we have an array of programs to help you find sobriety. Learn more about our treatment programs.


  1. Centers for Disease Control and Prevention. (2020). Understanding the Epidemic.
  2. Drug Enforcement Administration. (2019). Fentanyl (Trade Names: Actiq®, FentoraTM, Duragesic®).
  3. Centers for Disease Control and Prevention. (2020). Synthetic Opioid Overdose Data.
  4. National Institute on Drug Abuse. (2019). Fentanyl DrugFacts.
  5. Janssen Pharmaceuticals, Inc. (2009). Highlights of Prescribing Information, Duragesic.
  6. Centers for Disease Control and Prevention. (2020). Fentanyl.
  7. Centre for Addiction and Mental Health. (n.d.). Fentanyl.
  8. Drug Enforcement Administration. (2020). Alarming spike in fentanyl-related overdose deaths leads officials to issue public warning.
  9. County of Los Angeles Public Health. (n.d.). Fentanyl.
  10. World Health Organization. (2020). Opioid overdose.
  11. Schiller EY, Goyal A, Cao F, et al. Opioid Overdose. [Updated 2020 Aug 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
  12. Centers for Disease Control and Prevention. (2018). Opioids in the Workplace: Responding to a suspected opioid overdose.
  13. United States Drug Enforcement Administration. (2018). 2018 National Drug Threat Assessment.

About The Contributor

Ryan Kelley, NREMT
Ryan Kelley, NREMT

Medical Editor, American Addiction Centers

Ryan Kelley is a nationally registered Emergency Medical Technician and the former managing editor of the Journal of Emergency Medical Services (JEMS). During his time at JEMS, Ryan developed Mobile Integrated Healthcare in Action, a series... Read More

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