Fentanyl Overdose: Signs, Symptoms, and Treatment

Opioid overdose has serious health risks, including permanent injury and life-threatening loss of oxygen. Synthetic opioids, including fentanyl, were linked to over 36,000 overdose deaths in 2019. Instances of fentanyl overdose increased in 2020 as the COVID-19 pandemic accelerated the overall number of opioid overdoses, especially synthetic opioid overdoses.1

In this article:

What Happens During a Fentanyl Overdose?

Opioid drugs, including prescription fentanyl and illicit fentanyl analogs, are central nervous system depressants that affect the entire body. Opioids attach to receptors in the brain, producing feelings of calm, sleepiness, and detachment.

During a fentanyl overdose, major body system function becomes inhibited, including normal oxygen flow throughout the brain and body. As an overdose happens, the body experiences:2

  • Brain: Lack of oxygen affects the ability to think and send signals to the rest of the body. Seizures may occur. Brain damage can occur after four minutes if breathing stops.
  • Lungs: The effects on the brain slow and may stop breathing. Secondary lung complications can also occur, such as pulmonary edema where fluid fills the space between the lungs and can cause foaming at the mouth. Respiratory problems can lead to vomiting, aspiration, choking, and a risk of suffocation.
  • Veins: Opioids suppress normal blood flow, which can lead to vein collapse. This affects a person’s ability to move during the overdose and can cause permanent damage afterward.
  • Heart: When the brain is compromised, so is normal heart function. Heart rate may slow or become irregular. Heart attack may occur.

Who is at Highest Risk of Fentanyl Overdose?

Fentanyl overdose can occur any time you take fentanyl in a way not prescribed by a doctor. Because fentanyl is approximately 50-100 times stronger than morphine, the risk of fentanyl overdose is significant, even at extremely low doses.1

Even individuals who do not use fentanyl intentionally may be exposed to it. Fentanyl is not detectable by taste or smell and is often cut with illicit drugs like heroin to increase their potency. Counterfeit prescription pills may also contain fentanyl.3

The World Health Organization identifies the following risk factors for opioid overdose, including fentanyl overdose:1

  • Taking prescription opioids while not under the care of a doctor
  • Taking an extremely high dose of prescription opioids (the equivalent of or more than 100mg of morphine daily)
  • Administering opioids by injection
  • Using opioids with other central nervous system depressants, such as alcohol, anti-anxiety medication, and sleep aids
  • Having a co-occurring medical disorder, such as liver or lung disease, or mental health condition
  • Resuming opioid use after a period of abstinence
  • Having opioid use disorder (opioid addiction)

No use of fentanyl not under a doctor’s direct supervision is safe. If you or a loved one uses fentanyl or other opioids without a prescription or not as prescribed, be alert for the signs of an overdose and know how to get emergency medical help.

What Are the Signs of Fentanyl Overdose?

If you take fentanyl or are with someone who does, be aware of warning signs that indicate an overdose.

Signs of a fentanyl overdose include:3

  • Extremely small, “pinpoint” pupils
  • Pale or bluish skin, especially blue nail beds
  • Cold body temperature
  • Extreme drowsiness, including an inability to stay awake
  • Limpness in the limbs or body
  • Slow, shallow breathing
  • Loud breathing that may sound like gurgling or choking
  • Slow or undetectable heartbeat
  • Unconsciousness and no response to stimuli such as loud noises

How Can You Tell an Overdose From Intoxication?

Fentanyl use can cause “highs” that make a person less energetic and change their vital signs. Someone high on fentanyl or other opioids might act confused or have decreased awareness. But generally, they will be able to be awakened if they “nod off.”

During a drug overdose, a person becomes progressively less responsive to the degree that they may stop breathing entirely. Try to rouse the person by:4

  • Calling their name loudly
  • Touching their arm or shoulder
  • Rubbing your knuckles against their sternum

Things to Avoid if You Suspect a Fentanyl Overdose

When attempting to rouse a person during a suspected fentanyl overdose, do not:4

  • Induce vomiting–Vomiting can lead to fluid aspiration (i.e., the person inhaling vomit) or suffocation if their airway is obstructed.
  • Administer any unapproved substance–Do not inject or otherwise administer any substance except naloxone.
  • Aggressively try to wake the person–If you cannot rouse a person with your voice or touch, do not slap or otherwise try to forcefully wake them as this may cause additional injuries.
  • Place them in water–Do not use cold water or a shower as a semi-conscious person is at high risk of falling, going into shock, or drowning.

If you are unable to wake them, then it’s likely that they have overdosed and need emergency help. Call 911 immediately if you suspect an overdose on fentanyl or any other drug. Give the operator as much information as possible, such as what they took, how much, their age, their weight, and any other information they ask for. Stay by the person’s side until first responders arrive. You can roll them onto their side in recovery position to prevent them from swallowing their vomit.

Can Fentanyl Overdose Be Treated?

Fentanyl overdose is a major medical emergency that can result in permanent brain damage, coma, or death. If you think someone with you is experiencing an overdose from fentanyl or any other substance, call 911 and follow the operator’s instructions.

Breathing Support

The primary concern during an opioid overdose is the slowing and potential stopping of the person’s breathing. The 911 operator may instruct you to take actions that support a person’s breathing, such as changing their position to ensure that their airway is clear.


The respiratory effects of an overdose triggered by an opioid, like fentanyl, can be reversed using naloxone (Narcan). Naloxone is an opioid agonist. When administered, it attaches to the opioid receptors in the brain, blocking the effects of other opioids.5

If you have naloxone available, you can administer it to temporarily restore breathing during a fentanyl overdose. It can take up to 5 minutes for naloxone to restore breathing.

Naloxone is available as a nasal spray (Narcan, Kloxxado) and injection (Zimi). If you or someone you love is at high risk of opioid overdose, you can get naloxone:

  • With a prescription from your doctor
  • At your local pharmacy, sometimes without a prescription depending on the laws in your state
  • Through community distribution services or local health groups
  • Through your local health department

Naloxone is not a cure for fentanyl overdose.5 Naloxone is a short-acting medication that is intended to lengthen the period of time in which first responders can arrive without a person suffering serious or life-threatening overdose effects.

First responders, including police officers and firefighters, may also use naloxone to revive someone who has apparently had an opioid overdose.

Emergency Medical Response

Emergency medical services (EMS) responders take measures to support or restore breathing, such as providing rescue breathing, oxygen, and naloxone. EMS monitors breathing and known complications of fentanyl overdose while transporting the person to a hospital.

Opioid toxicity can reoccur for at least four hours after the initial overdose.4 Medical monitoring of breathing, opioid withdrawal symptoms, and potential medical complications continues while the person is transported to the hospital and transferred to emergency staff there.

Continued Medical Care

Individuals are often admitted to a hospital after an overdose. At the hospital, staff can treat recurring opioid toxicity, address any additional breathing problems, assess symptoms of opioid withdrawal, and perform brief motivational interventions to encourage the individual to enter detox treatment after they are medically stable enough to do so.

How is Fentanyl Misuse and Addiction Treated?

While overdose can occur after any fentanyl misuse, it can indicate the need for substance misuse or addiction treatment.

Withdrawal Management

Fentanyl withdrawal can cause unpleasant and potentially serious symptoms, including vomiting, sleep issues, and mental health symptoms. Withdrawal management services, often referred to as “detox,” provide medical supervision until the withdrawal period ends.

Depending on the severity of symptoms, detox center staff may monitor vital signs, provide medication to manage withdrawal symptoms, and offer additional services like counseling.

Medication-Assisted Treatment

Most treatment plans for fentanyl addiction include medication-assisted treatment (MAT). The most common medications used to treat opioid use disorders are:6

  • Methadone–Methadone is an opioid agonist used to reduce the desire to use opioids. It can be prescribed while you are still experiencing active withdrawal symptoms and be continued as long as needed.
  • Buprenorphine–Buprenorphine reduces the desire to use opioids, but also affects the intensity of cravings and urges. It is typically prescribed once symptoms are less severe.
  • Naltrexone–Naltrexone is generally used as a relapse prevention tool because it takes away the ability to get “high” from opioids. You must be completely detoxed and not have any opioids in your system before starting naltrexone.

Suboxone, which is a brand name medication including both buprenorphine and naloxone, may also be used.

Behavioral Therapy

Detox and medication-assisted treatment address the physical symptoms of stopping opioid misuse, but they are not treatment for the underlying causes of addiction. Fentanyl addiction treatment programs include behavioral and psychoeducational treatments to address the addiction itself, not just its effects.

If you struggle with fentanyl misuse or have experienced a fentanyl overdose, call 800-914-7089 (Info iconWho Answers?) to discuss opioid addiction treatment options with a treatment specialist.


  1. World Health Organization. (2021, August 04). Opioid overdose.
  2. MinutesMatter. (2020). What Happens to the Body During Opioid Overdose?.
  3. Centers for Disease Control and Prevention. (2022, February 23). Fentanyl Facts.
  4. Substance Abuse and Mental Health Services Administration. (n.d.). Five Essential Steps for First Responders. Opioid Overdose Prevention Toolkit.
  5. National Institute on Drug Abuse. (2022, January 11). Naloxone DrugFacts.
  6. American Society of Addiction Medicine. (2016). Opioid Addiction Treatment: A Guide for Patients, Families and Friends.
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