Fentanyl and other drugs like it are synthetic drugs—they’re made in a laboratory using chemical compounds instead of being extracted from plants and other natural sources. Developing drugs in a lab allows scientists to create stronger and better medicines than what nature can do alone, but it can have a downside. Changing the chemical structure of a synthetic drug can create something entirely new.

For example, carfentanil is a fentanyl derivative, a chemically modified version of its parent drug. It’s 100 times more powerful than fentanyl itself and is so strong that it’s never been approved for use in people. While carfentanil has a legitimate application as a tranquilizer for large animals such as elephants, it’s increasingly turning up in the illegal drug supply. As of 2025, the DEA detected illicit carfentanil in 37 states. That number is expected to climb.

Medetomidine and xylazine are other synthetic animal tranquilizers that cartels use in fake pills and street drugs.  Xylazine can lead to an overdose when it’s mixed with fentanyl, and medetomidine is 100 times more powerful than xylazine. Like fentanyl, none of these drugs are detectable to the naked eye.

Drug cartels continue to chase profit, looking for whatever they can make and sell fast. That’s why the amount and kind of synthetic drugs in the illegal drug supply is constantly changing—and that makes it even more deadly.  Currently, no one test strip detects them all. Plus, while naloxone (Narcan) can work to reverse overdoses caused by fentanyl and other opioids, medetomidine and xylazine are not opioids, so it may take multiple doses of Narcan to save a life.

When there’s no easy, foolproof way to detect them, the only way to stay completely safe from these deadly synthetic drugs is to never use pills or recreational drugs bought online or on the street.