Medically Reviewed

Fentanyl Side Effects: Mental & Physical Effects of Fentanyl Use

3 min read · 5 sections

Fentanyl carries many potential health risks when used by itself or in combination with other drugs. The Centers for Disease Control (CDC) reports that 71,000 overdose deaths in 2021 involved synthetic opioids like fentanyl.1

This page will discuss fentanyl, its risks and health effects, and fentanyl addiction treatment.

What is Fentanyl?

Fentanyl is a fully synthetic opioid 50 to 100 times more potent than morphine. Fentanyl is sometimes prescribed for legitimate medical reasons; however, it is also commonly synthesized in illicit labs and sold on the black market.2

Prescription fentanyl may be prescribed to treat relatively severe pain. In its various formulations, prescription fentanyl may be administered as an injectable solution, transdermal patch, or lozenge.2

Much of the opioid overdose crisis in recent years has involved illicitly manufactured fentanyl (IMF). Illicit forms of fentanyl are sometimes sold in powder or liquid form or pressed into pills that resemble prescription medications.2

While fentanyl is often sought after by people who use opioids, many people risk taking fentanyl unknowingly by using other illicit drugs. Fentanyl’s role in overdoses today is partially due to many illegal drug distributors intentionally mixing fentanyl with other substances, (e.g., methamphetamine, heroin, and cocaine) to drive down their costs of production (and therefore increase their profits).2 For people who have built no tolerance to opioids—and even for those who have—consuming fentanyl unknowingly with other drugs can be extremely dangerous.3

Unfortunately, it is sometimes impossible to tell with the naked eye whether illicitly manufactured drugs, such as heroin, MDMA, cocaine, and methamphetamine, contain trace amounts of fentanyl. For example, a legally manufactured oxycodone pill and a counterfeit one laced with a lethal amount of fentanyl may be indistinguishable from each other without conducting a test.4

Anyone who uses fentanyl—whether using transdermal fentanyl patches, prescription pills, injecting fentanyl, snorting fentanyl, or smoking the drug—is subject to experiencing a range of adverse (and potentially deadly) effects. Fentanyl use of any kind is potentially even more risky for people who suffer from obstructive airway diseases (such as asthma), suffer from liver failure, are hypersensitive to or allergic to certain fillers in fentanyl, or whose tolerance to opioids is low.3

Polysubstance use can pose additional risks to people who consume fentanyl. The presence of other drugs, such as alcohol and opioids, can exacerbate fentanyl’s potential negative effects and create complex and dangerous medical scenarios.3

One major potential adverse effect of fentanyl misuse is the development of an opioid use disorder (OUD), or addiction to fentanyl.1 OUD is characterized by someone’s inability to stop using fentanyl, despite negative life consequences—such as those related to work, school, and social/personal affairs.3,5

Illicit fentanyl is often used via injection.2 Injecting fentanyl is associated with dangers aside from the adverse pharmacological effects of the drug itself. For example, If someone injects fentanyl or another drug mixed with fentanyl with a nonsterile needle, their risk of contracting HIV or viral hepatitis increases substantially. People who inject fentanyl through nonsterile needles also risk the potential of developing heart or skin infections.6

Can you Overdose on Fentanyl?

Yes, fentanyl carries a very high risk of overdose because it is lethal in such small amounts. Synthetic opioids, which include fentanyl, are currently the main driver of overdose deaths in the United States.2 Fentanyl’s high level of potency greatly contributes to its risk for overdose and other adverse reactions.3

Fentanyl overdose typically occurs when the drug stops or slows someone’s breathing to the point that the brain becomes depleted of oxygen, a condition known as hypoxia. Hypoxia can result in coma, brain damage, and death.2

Symptoms of Fentanyl Overdose

Recognizing the signs of an opioid overdose and acting quickly can save someone’s life. The following symptoms are known as the classic “opioid overdose triad” when it comes to toxic doses of opioids:7

  • Small pupils.
  • Respiratory depression (slow, ineffective breathing).
  • Loss or decreased level of consciousness.

How Can a Fentanyl Overdose be Treated?

Reversal of fentanyl overdose is possible if appropriate action is taken in a timely manner.8

If you believe someone is overdosing on fentanyl:8

  1. Call 911.
  2. Administer Narcan (naloxone) if it is available. Administer another dose every 2-3 minutes if they do not respond.
  3. Support the person’s breathing (clear their airway, begin rescue breathing if necessary).
  4. Turn the person on their side to prevent choking.
  5. Stay with them until medical help arrives.

Fentanyl Addiction and Treatment

Though the adverse effects of fentanyl, including overdose, may be experienced with even a single instance of use, they could also be part of a larger opioid addiction or other substance use disorder. People with significant opioid dependence often benefit from medically supervised detox to manage their withdrawal symptoms, followed by further treatment to address many of the more psychosocial aspects of their addiction.10,11

Treatment for opioid dependence and opioid use disorders may consist of:

  • Medically managed withdrawal: This is usually the first step in treatment. In this type of treatment, the patient is monitored by a medical team to ensure that their withdrawal from fentanyl is managed safely and effectively.10
  • Inpatient rehab: The person lives at a facility for the duration of treatment where they receive 24-hour care. This option is ideal for people with relatively severe addictions and addiction-related issues, as well as for people struggling with co-occurring disorders.11
  • Outpatient treatment: The person receives treatment on an outpatient basis and is able to return home or other residence outside of treatment hours. Outpatient treatment often involves behavioral therapeutic sessions several hours a day throughout the week.11
  • Mental health counseling: Behavioral therapies can assist with altering maladaptive behaviors and formulating relapse prevention plans.11
  • Medication: Medications for opioid use disorder (MOUD) can help people reduce their withdrawal symptoms and cravings and maintain their recovery momentum. These are often administered during detox as well as prescribed long-term.11

To learn more about the types of treatment available for opioid use disorders, visit our opioid rehab program page.

American Addiction Centers (AAC) is here to help you with obtaining addiction treatment for you or your loved one. Addiction treatment works and there are many fentanyl rehab options available to you. AAC’s skilled admissions navigators can answer any questions you have and help guide you through the process of finding the right treatment option for you.

Contact us at to get started with substance use disorder treatment today.[/callout]

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