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Opioid Addiction: Why Is Fentanyl So Dangerous?

Contributors Joji Suzuki, MD and Sarah Wakeman, MD
4 minute read
One teen girl comforts another.

Fentanyl is a powerful drug that was designed to be used as a pain-relieving medicine called an analgesic. But it has come to play a major role in drug overdoses and substance use disorders across the United States.

In this article, Joji Suzuki, MD, MSc, a Mass General Brigham psychiatrist, answers common questions about fentanyl and signs and symptoms of opioid addiction. Dr. Suzuki is director of the Division of Addiction Psychiatry at Brigham and Women's Hospital.

Where does fentanyl come from?

To understand where fentanyl comes from, it helps to know what opioids really are.

“Opioids occur in our brains and also are made from plants or in a lab,” explains Dr. Suzuki. “In our brain they’re called endorphins, and they actually function naturally inside.”

There are 3 classes of opioids:

  1. Naturally occurring opioids. These are derived from plants. “The most famous example is opium, taken from poppy plants,” says Dr. Suzuki. “You get morphine out of it.”

  2. Semisynthetic opioids. These are derived from natural opioids (like morphine) and tweaked in a lab to create something new. “Heroin is a good example,” he says.

  3. Synthetic opioids, like oxycodone and fentanyl. These are man-made drugs created in a lab. “They have no equivalent naturally occurring versions,” Dr. Suzuki explains.

What causes opioid addiction?

Like many health conditions, addiction is due to a combination of genetic and environmental risk factors. Adverse childhood experiences, like trauma and early life stressors, greatly increase the risk of addiction. While addiction to opioids can sometimes begin when patients take prescription opioids for medical reasons, prescription opioid misuse most commonly occurs among people who already misuse other substances. For example, among young people who misuse prescription opioids, 63% have used cannabis and 21% have used cocaine. Some patients may use prescription opioids for chronic pain. Others may take them to relieve pain from a surgical procedure.

“Unfortunately, for someone at risk, prescription opioid use can continue and escalate,” says Dr. Suzuki. “Eventually it can lead to taking something like heroin as well as fentanyl.”

Fentanyl is about 50 to 100 times more potent than heroin. That’s why it’s had such a devastating consequence on the opioid crisis today.

Joji Suzuki, MD
Mass General Brigham

What are the warning signs of addiction to opioids?

It’s hard to recognize addiction in ourselves, Dr. Suzuki explains. “Early on, a person probably could have stopped using fentanyl if they wanted to. But there was no perceived need because there wasn't as much harm associated with use. But as the harm accumulates and becomes more disruptive, it becomes harder and harder to stop."

Some early symptoms of opioid addiction include behaviors like:

  • Taking more than prescribed or intended
  • Not being able to cut back or stop despite trying
  • Going to different doctors or emergency rooms to try to get opioids
  • Changes in mood
  • Changes in academic or work performance
  • Giving up other activities because of use
  • Using despite it causing relationship problems
  • “Nodding off,” or appearing sedated

A person who is intoxicated on opioids may also have “pinpoint pupils.” This means their pupils are small, even when exposed to bright light.

Why is fentanyl so dangerous?

Fentanyl is often added to other illicit pills and powders without people’s knowledge. This is because it costs less to produce than other opioids, and because a small amount goes a long way. In Boston, in fact, heroin is rarely found in the illicit supply.

"Fentanyl is about 50 to 100 times more potent than heroin," explains Dr. Suzuki. “That’s why it’s had such a devastating consequence on the opioid overdose crisis today.”

The unpredictability of the illicit drug supply is a major reason that overdose deaths are increasing. People often don’t know whether the pill or powder they bought from an illegitimate source contains a lethal dose of fentanyl.

If you or a loved one is struggling with addiction, remember: Recovery is possible and we have several effective treatments available now, including medication treatments for opioid addiction. This reduces the risk of death and improves the likelihood of recovery. A substance use disorder is a treatable health condition. And like many health conditions, people with substance use disorders may need to try several different treatments before they find one that fits. With support and the right resources, you can begin your recovery journey.

Mass General Brigham Substance Use Disorder Program

Our Bridge clinics are transitional outpatient addiction clinics for patients in need of rapid access to substance use disorder care. Our four regional Bridge clinic hubs serve patients from any Mass General Brigham location and community members through both in-person and virtual care:

  1. Brigham and Women’s Hospital Eliza Dushku Palandjian and Peter Palandjian Bridge Clinic
    75 Francis Street, Suite 159
    Boston, MA 02115
    Phone: (617) 278-0172

  2. Massachusetts Hospital Bridge Clinic
    55 Fruit Street, Cox 1, Suite 110
    Boston, MA 02114
    Phone: (617) 643-8281

  3. Merrimack Valley Bridge Clinic
    600 Primrose St. Suite 100
    Haverhill, MA 01830
    Phone: (978) 469-5536

  4. Salem Hospital Bridge Clinic
    55 Highland Ave Suite 201
    Salem, MA 01970
    Phone: (339) 229-7683

Joji Suzuki, MD


Sarah Wakeman, MD


General Internist