Carfentanil is a synthetic analogue of fentanyl. It is so potent that extremely small doses have the potential to cause life-threatening symptoms or overdose. Patients buying what they believe to be regular heroin or fentanyl can sometimes be given Carfentanil, leading to increased risk of opioid overdose and even death.
Key Facts About Carfentanil
Some key facts about carfentanil and the opioid epidemic include the following:
- Carfentanil is an extremely potent fentanyl analog, contributing to what is referred to as the “third wave” of America’s opioid epidemic - the “fentanyl era”. 
- In 2016 and 2017, there were huge increases in overdose deaths (11,228 and then 6,605) across the US. While there are a number of potential contributing factors to this increase, a 2020 study linked much of this increase in overdose deaths to Fentanyl analogues, including carfentanil. 
- According to the U.S. Department of Health and Human Services, two out of three overdose deaths in 2018 involved the use of opioids including fentanyl and Carfentanil
How Potent and Addictive Is Carfentanil?
Carfentanil is potentially 10,000 times more potent than morphine and 100 times more potent than fentanyl. This substance is so potent that the DEA has released statements to officers detailing concerns about accidental exposure, as even very tiny amounts getting into the body has the potential to be fatal (discussed more later).
The more potent an opioid is (in general), the more addictive it is. Thus, Carfentanil, and Fentanyl, is considered to be extremely addictive.
How to Recognize Carfentanil
Like many drugs, it isn’t really possible for a layperson to recognize carfentanil by sight, especially if trying to differentiate it from similar drugs like heroin, cocaine or fentanyl. Like these other drugs, it usually comes in a powder form. It can come in a number of different colors, depending on if it was dyed, or what other substances it was cut with. It can come in other forms as well, including powder, blotted paper, or sprays.
It can be identified with specialized equipment, but that isn’t very helpful for an individual purchasing or otherwise intending to use illicit drugs. There are inexpensive drug tests that can detect fentanyl that can be used by lay-people to test their drugs to see if they include fentanyl, but these can be hard to obtain and can be falsely negative.
Any substance purchased illicitly has the potential to contain fentanyl or carfentanil, especially these days.
How Carfentanil Affects the Body
Carfentanil is an opioid and has a similar mechanism of action to the other drugs in this category. Opioids act on opioid receptors in the brain, causing analgesia, decreased pain, loss of inhibitions, euphoria and feelings of pleasure, and, more worrisomely, sedation, respiratory depression and eventual overdose.
A Lethal Dose of Carfentanil
Exact studies haven’t been done to identify how much carfentanil is fatal to humans, but fentanyl can be fatal in doses as small as 2 mg depending on the way it is administered. Carfentanil is potentially 10,000 times as potent as fentanyl. Importantly, the biochemistry of drugs means this doesn’t necessarily mean a fatal carfentanil dose is exactly 10,000 times smaller than a fatal fentanyl dose, but it does make for a good starting point in understanding how little carfentanil can still cause fatal effects in the human body.
For reference, 2 mg of powder can easily sit on the head of a penny.
Common Street Names for Carfentanil
Carfentanil doesn’t appear to be popular enough to have developed any widespread street names specific to it. However, it is closely associated with fentanyl, and it will often be sold under fentanyl’s street names, which include the following:
- China girl
- China town
- China white
- Dance fever
- Great bear
- Tango & cash