Carfentanil, a synthetic opioid significantly more potent than fentanyl, is experiencing a dramatic increase in use across the United States, according to reports from drug enforcement and health officials.

The substance, originally developed as a tranquilizer for large animals, has been detected with increasing frequency in the illicit drug supply. Law enforcement agencies report that carfentanil is being used as a substitute for fentanyl in street drugs.

Health officials say the resurgence has resulted in hundreds of overdoses among drug users who were unaware they had consumed the substance. Carfentanil is estimated to be 100 times more potent than fentanyl and 10,000 times more potent than morphine.

The drug poses significant risks not only to users but also to first responders and law enforcement officers who may be exposed to even microscopic amounts during investigations or overdose responses. Standard naloxone doses used to reverse opioid overdoses may be insufficient for carfentanil poisoning.

Carfentanil previously emerged as a major concern in the US drug supply around 2016-2017, contributing to record overdose deaths before its presence declined. The current resurgence represents a troubling development in the ongoing opioid crisis that continues to affect communities nationwide.