Fentanyl: What Is a Lethal Dosage?

Fentanyl is a powerful opioid drug with a primary medical use for the control of moderate to severe pain. Fentanyl may be administered as a transdermal patch, injected, or taken in pill or liquid form.

Fentanyl is also manufactured illegally and sold on the black market, often appearing as an adulterant in street drugs or counterfeit prescription pills. Illicitly manufactured fentanyl and other synthetic opioids are the primary drivers of overdose deaths in the United States.¹

What Is the Lethal Dose of Fentanyl?

Because of the proliferation of fentanyl and its role in the overdose epidemic, many people wonder what a lethal dose is.

Unfortunately, there is no simple answer to this; a dose that may be fatal for one person may not be fatal for another. The risk of overdose is compounded by many potential variables, such as the presence of other substances, the person’s general health, their tolerance to opioids, and more.

The bottom line is ANY misuse of fentanyl (knowingly or unknowingly) has the potential to cause a fatal overdose. 

Effects of Fentanyl

Fentanyl effects may include:²

• Euphoria.
• Drowsiness.
• Constipation.
• Nausea.
• Confusion.
• Difficulty breathing.
• Loss of consciousness.

Over time, chronic use of fentanyl can lead to physical dependence, addiction, and other lasting effects on the brain and body. However, even a single dose of fentanyl is often enough to cause fatal overdose.

Fentanyl Overdose Symptoms

The signs and symptoms that occur in individuals who have overdosed on fentanyl can consist of:

• Extreme drowsiness, lethargy, lightheadedness, or dizziness.
• Marked difficulty with balance, difficulty with walking, and decreased motor coordination.
• Complaints of nausea and vomiting.
• Significant mental status changes that often include slurred speech, decreased speed of thought (that can be observed by extremely slow rates of speech), confusion, irrational actions, and/or aggressiveness.
• Pinpoint eye pupils and/or bluish or purplish lips, hands, feet, fingernails, and/or toenails.
• Noticeably slowed or shallow breathing (In some cases, people may stop breathing or produce gurgling noises.).
• A marked reduction in blood pressure and heart rate.
• Becoming unconscious or comatose.

The lethal effects that occur because of fentanyl overdose are usually due to significant respiratory suppression or the complete halting of breathing caused by the central nervous system depressant effects of the drug.

What to Do If Someone Has Overdosed on Fentanyl

If one suspects that someone has overdosed on fentanyl, several actions should be taken:

• Contact medical emergency services (call 911) immediately.
• Do not attempt to perform CPR or administer any medications unless you are trained to do so.
• If the person is still breathing, roll them on their side so they will not choke if they vomit.
• Trained individuals can place the person in the standard recovery position and ensure that the person’s airways are free of obstructions.
• Do not administer any fluids. Just stay with the person and make sure they are breathing until help arrives.
• Individuals trained to administer naloxone can save the person’s life if the drug is available.

Narcan (naloxone) is an opioid antagonist medication that immediately attaches to the opioid receptors in the brain when administered, removes any opioid drugs that are attached to those receptor sites, and initiates an immediate withdrawal response. If naloxone can be administered quickly enough, a potentially fatal situation can be avoided. Some communities are offering training in Narcan use. You can also watch our video below.

Fentanyl is an extremely potent opioid drug. Individuals can experience potentially fatal effects from extremely small amounts of the drug. If fentanyl is taken in conjunction with other opiates, its lethal dose is even smaller.

Fentanyl Addiction Treatment & Detox in Mississippi

Many people with opioid use disorder (OUD)—the clinical term for opioid addiction—require formal treatment to get sober and remain in recovery. Treatment for OUD often includes medications for opioid use disorder (MOUD), behavioral therapy, peer support, and other interventions.

Oxford Treatment Center, our inpatient drug rehab in Mississippi, offers evidence-based treatment for addiction to fentanyl and other substances. We also offer safe medical detox, intensive outpatient drug and alcohol treatment, partial hospitalization, and sober living options that can help you or your loved one get started on the path to recovery.

If you are interested in learning more about rehab admissions, what to expect in inpatient rehab, or want to discuss paying for addiction treatment, please reach out to our caring admissions navigators at any time of day or night.

You can also verify your insurance coverage at Oxford using the confidential .