Carfentanil – The Most Potent Opioid

Carfentanil was first synthesized by a team of chemists at Janssen Pharmaceutica in 1974.

Janssen Pharmaceutica is Johnson & Johnson Innovative Medicine, a pharmaceutical company headquartered in Belgium and owned by Johnson & Johnson.

It is an analog of the synthetic opioid analgesic called fentanyl. Analogs are substances that are substantially similar in chemical structure.

It’s one of the most potent opioids known at this time and the most potent opioid used commercially. The potency of the drug is approximately 10,000 times that of morphine and 100 times that of fentanyl.

Anesthetic for Large Animals

Today, it is marketed under the trade name Wildnil. Carfentanil is closely related to fentanyl on a chemical level and has similar effects. It has never been approved for human use and is a general anesthetic agent for large animals, such as elephants, horses, and bears.

Its strong potency makes it inappropriate for human use. Its effect on the human body can start with a dose of less than 1 microgram (less than a grain of salt). It has no odor or color and is highly soluble in water so carfentanil is not easily identifiable by users. Often found mixed with heroin in the U.S. and Canada, making an already dangerous opioid all the more powerful and lethal.

 Horse grazing in the field

Carfentanil is Lethal

Carfentanil is not a substitute for fentanyl, it is lethal when ingested, inhaled or with external contact even in very small amounts. A drop of carfentanil absorbed through the skin after an accidental contact could result in death.

Before its entry in Canada and the U.S., many addicts in Lithuania and Estonia knowingly misused the drug carfentanil. In North America, the drug is mixed into heroin and other drugs to make it cheaper and increase sales.

Individuals using opioids are often unaware that the substance they’re buying is laced with Carfentanil. Which can result in an overdose.


A carfentanil overdose is not as easily reversed with the use of naloxone (used to treat a narcotic overdose) and may need several shots to have its effect. Because carfentanil is so potent, it will quickly reach toxic levels in the human body. Here are the signs and symptoms of overdose:

  • Shallow or absent breathing
  • Dizziness, lethargy, sedation
  • Loss of consciousness
  • Nausea, vomiting
  • Heart failure, weak or absent pulse
  • Cold, clammy skin

These are withdrawal symptoms of carfentanil:

  • Cravings
  • Shakiness
  • Chills
  • Anxiety
  • Insomnia
  • Nausea
  • Vomiting
  • Hypersomnia (trouble staying awake)
  • Diarrhea
  • Delusions
  • Seizures
  • Changes in appetite


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