What the Heck is Carfentanil—the Synthetic Opiod Used to Knock Out Elephants?

Have I been living under a rock? One of our Montana writers used the word "carfentanil" in a headline and I thought it was a typo, perhaps they meant to say "car fentanyl," but no. Turns out it's a thing.

Carfentanil is an extremely potent synthetic opioid — estimated to be 100 times stronger than fentanyl and 10,000 times more powerful than morphine. Originally developed as a tranquilizer for elephants and other large mammals, it has been increasingly detected in the illicit drug supply across the United States, including Wyoming.

Carfentanil is not common in a general sense, but its prevalence in the illicit drug supply is rapidly increasing, making it a growing public health threat.

The Wyoming Department of Health warns that users are often unaware they’re consuming synthetic opioids like carfentanil, which can be mixed into other substances such as fentanyl, heroin, or counterfeit pills made to look like legitimate medications like oxycodone or Xanax.

Carfentanil was confirmed in Wyoming in late 2024, when Casper Police Chief Keith McPheeters reported three near-fatal overdoses involving the drug. Authorities say even minimal exposure can be life-threatening, not just to users but also to first responders and medical personnel, since the substance can be absorbed through the skin or accidentally inhaled.

“This is not something you can safely touch,” McPheeters said. “It’s lethal in amounts too small to see.”

Because of its potency, standard doses of naloxone (Narcan) may not be enough to reverse an overdose. Officials recommend administering multiple doses if carfentanil exposure is suspected.

While Wyoming doesn’t yet track carfentanil-specific data, it’s part of a broader surge in synthetic opioid deaths. According to the Department of Health, synthetic opioid-involved fatalities in Wyoming quadrupled between 2018 and 2021. In 2022, 48 of the state’s 93 overdose deaths were linked to fentanyl.

The DEA and state officials continue to emphasize their “One Pill Can Kill” campaign, warning that any pill not prescribed by a doctor could contain a lethal dose of fentanyl or carfentanil.

What Carfentanil Looks Like

Powder: Fine, white, and easily mistaken for drugs like cocaine or heroin.

Pills: Counterfeit pills containing carfentanil have been seized in a range of colors and markings, mimicking real prescription medications.

Mixtures: Often cut into other drugs to increase potency, making it nearly impossible for users to know what they’re taking.

Size: Just one or two grains of salt worth can be fatal.