Written by: THE BALANCE
Medically reviewed by Dr. Sarah Boss, MD
Last updated: January 19, 2026
Fact checked
Quick Summary
  • It is the latest drug in the illicit opioid family that has shaken the United States to its core.
  • Recently it has hit the news because of cases of opioid toxicity and opioid-related deaths.
  • According to the National Institute on Drug Abuse, 36 million people worldwide now have an opioid-use disorder, and some of the opioid-related deaths are due to carfentanil.

Carfentanil is the new kid on the block. It is the latest drug in the illicit opioid family that has shaken the United States to its core. Recently it has hit the news because of cases of opioid toxicity and opioid-related deaths. According to the National Institute on Drug Abuse, 36 million people worldwide now have an opioid-use disorder, and some of the opioid-related deaths are due to carfentanil. Common street names of the drug include “drop dead”, “C. 50”, and “serial killer”. Some other names are China girl and China White. When it is combined with other opiates, it is called gray death. 

Carfentanil is a synthetic opioid and has been derived from fentanyl. It was originally made to be used on very large animals like elephants to sedate and treat them. It is often added to other illicit opioid drugs like heroin and is seen to be a part of counterfeit opioid pills which are the exact replica of prescription pills. Adding carfentanil to these pills gives an extra kick or punch to these pills but it comes at great risk of toxicity which can rapidly prove to be fatal. There is nosure-shott way of knowing if carfentanil has been added to the pills as it cannot be tasted or smelled. So on account of its potency and toxicity, only a very small amount can kill you, 

Carfentanil is the strongest known synthetic opiate and is used in substance use disorder. It is more potent than either fentanyl or morphine, and heroin is often laced with Carfentanil to produce an extra kick or euphoria. It is approximately 10,000 times more potent than morphine and 5000 times stronger than heroin. In fact, heroin which is laced with Carfentanil may lead to overdose, hypotension, constricted pupils, and respiratory depression and may prove to be rapidly fatal. (source: NIDA, 2024)

It is often illegally smuggled into the United States and has the potential to be used in bioterrorism as a weapon of mass destruction. It is so potent that it can exert its adverse effects even by touching or smelling it. It is advisable to use gloves while handling this lethal drug. It is not legally licenced for use in humans in the United States. 

Carfentanil is highly addictive. It acts by binding to the opioid receptors in the brain. It is so toxic that only 2 mg of the drug is sufficient to sedate an animal like an elephant. Owing to its extreme addiction and potency, street dealers have found it very profitable to mix it with other drugs, particularly heroin and fentanyl. It is 100 times stronger than fentanyl, which is the parent drug. Fentanyl is 50 times more potent than morphine. That gives us an idea about its addiction potential. (source: DEA, 2024)

This drug produces long-lasting effects as the body takes hours to metabolize it. So, the euphoria and the “high” from carfentanil can last hours. This increases its appeal to drug users who crave the prolonged kick absent in some other drugs. 

Carfentanil belongs to the opioid group of drugs and shares its side effects and symptoms of addiction. Some of the side effects are given:  (source: NIH/NLM, 2023)

  • Itching
  • Nausea 
  • Vomiting 
  • Confusion 
  • Respiratory depression 
  • Dizziness 
  • Drowsiness 
  • Muscle aches 
  • Pinpoint pupils 
  • Sweating 
  • Restlessness 

As carfentanil is often illegally smuggled from China and the users may become addicted to the drug when it is mixed with heroin or other street drugs. Carfentanil addiction is very rare as it is not used in the pure form. It’s not commonly abused intentionally. It’s possible to have a fatal experience from overdose than to develop dependence or addiction. However, if you have taken carfentanil and have survived, it means that you have a very high tolerance for very strong opioids and may be at risk of considerable self-harm and even death.

You should consider seeking help for the disorder as it is curable. Addiction to this drug can take over your life completely and produce adverse effects in addition to pleasurable symptoms. These effects may take over your life completely till you become totally dependent on the drug to function. Some of the symptoms which suggest that you might have a drug addiction include the following:  (source: SAMHSA, 2024)

  • Intense craving of the drug 
  • Needing increased doses to produce the same effects 
  • Hiding drugs 
  • Confusion 
  • Change in appetite 
  • Change in weight 
  • Extreme anxiety 
  • Paranoia 
  • Failing to stop using it despite trying actively 
  • Flu-like symptoms 
  • Abdominal pain 
  • Lying about drug use 
  • Change in mood 
  • Sleeplessness or insomnia 

Some common signs that make you suspect that someone has a carfentanil addiction includes buying the drug online, using cocaine or opioids, and talking about the street name of the drug with friends and acquaintances. 

It can last for days to a month due to its high potency and long action. Its severe withdrawal symptoms may make it difficult to complete opioid withdrawal at home. Professional help may be needed. Please don’t be scared to seek help if needed. 

Carfentanil is the most potent known opioid in the world. Although it is derived from fentanyl synthetically, it is 100 times more powerful than fentanyl. It is 10,000 times more powerful than morphine and 5000 times stronger than heroin. Even a tiny overdose can lead to the rapid development of respiration depression, failure to breathe, and oxygen deprivation. It thus leads to death quickly.  (source: WHO, 2023)

Carfentanil overdose is the leading cause of death. It is very easy to overdose on this drug as it is present in street formulations, and the user may not be aware that he is taking it. It is available cheaply and adding it to heroin or fentanyl increases the profit margin, increases the potency, and gives the illusion of pure heroin. Moreover, inconsistent levels of drugs may be present in street drugs. What gives you a pleasurable high one day can potentially kill you the next day.

List Of Opioids Strongest to Weakest (source: StatPearls, 2025)

Approximately 28,000 overdose deaths occurred in the United States in 2017 due to synthetic opioids like fentanyl and carfentanil. If you are reading this, you might be worried about carfentanil overdose. A medical detox program may be the solution for your opioid addiction and can help you conquer your physical dependence on carfentanil and other opioids safely and effectively. 

Carfentanil has a very rapid onset of action which starts within minutes of taking the drug. It has a prolonged duration of action and can stay in the body for a longer period of time. It can easily cross the blood-brain barrier and act on the opioid receptors in the brain. It can cause shallow breathing, respiratory failure, heart failure, and ultimately coma and death. It often causes instant death even before the arrival of paramedics. Only a naloxone injection given timely, may help slow its absorption sufficiently for help to arrive. Multiple doses of the rescue medicine naloxone are not sufficient to fully reverse the actions of carfentanil. It is so powerful that even first responders and law enforcement personnel may fall victim to it. It is recommended to use protective equipment while handling the drug.  (source: StatPearls, 2025b)

Risk factors for carfentanil overdose 

There may be several risk factors for overdosing on the drug. Some of them include opioid use disorder, having a high concentration of opioids, using intravenous opioids, having a cocktail of drugs, needing more and more drugs to produce the desired effect, using opioids and carfentanil mixed with alcohol, caffeine, and other drugs.  (source: NIDA, 2024b)

Overdose of pure carfentanil is rare. As it is mixed with other drugs and not taken in a pure form, its exact signs and symptoms are unknown. It is thought that since it is an opioid, it’s overdose symptoms are essentially the same and include confusion, restlessness, agitation, shallow breathing, blue discoloration of the hands and feet due to lack of oxygen, respiratory depression, pinpoint pupils, vomiting, coma, and death. 

The lethal dose of carfentanil is unknown, but because of its extreme potency, it is extremely lethal. Only a minute amount of drugs can be responsible for a large number of deaths. Because of carfentanil’s potency, the effects on the human body and brain are very rapid. When even a fraction of the dose given to elephants is administered to people, it has a rapid onset and does not get treated with sufficient amounts of naloxone. 

FAQs

Can carfentanil cause death? 
Carfentanil is the most potent opioid drug available. It can cause extreme drowsiness or altered sensorium, cold, clammy skin, disorientation, blue hands and feet due to decreased oxygen, depressed breathing, sedation, and pinpoint pupils. The only hope of saving the patient is to administer one dose of naloxone before the arrival of the emergency personnel to slow down the process.

The street name gray death suggests that the body turns gray or blue due to the decreased oxygen-carrying capacity by the body. Historically it has caused the death of countless people in the Moscow theater incident (800 hostages) where it was used in an aerosol as a weapon of mass destruction, and the patients could not be revived in time. About 650 people were hospitalized. Every year many people in the United States due to heroin laced with carfentanil. 
Heroin vs fentanyl vs carfentanil- Which is more lethal? 
Carfentanil is the most toxic drug known and can even kill large animals like elephants. It is derived from the parent compound fentanyl and is approximately 100 times more toxic than fentanyl. It is 10,000 times more powerful than morphine and 5000 times stronger than heroin. Heroin causes a large number of opioid-related deaths every year so imagine the havoc carfentanil is creating.

If you are reading this article, you and your loved ones may be worried about the use of carfentanil. There is no way to recognize it as it is an odorless and tasteless white powder. Please do not hesitate to seek help as opioid use can be treated. There are a number of drugs available, and you can learn coping techniques that will help you deal with stress or other triggers that lead to opioid use in the first place.

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