Riverside County Public Health officials have confirmed the first fatal carfentanil overdose in the county, after a man in his 40s died from consuming the synthetic opioid earlier this year.

Carfentanil is a fentanyl derivative that is 100 times stronger than fentanyl and 10,000 times more potent than morphine, according to the United States Drug Enforcement Administration.

The death occurred in March, and county health officials noted that it can take months to confirm the cause of death.

Carfentanil was developed for use as a tranquilizer in large animals, such as elephants, and due to its potency, even a microscopic amount can cause a fatal overdose, according to the DEA.

"This white, powdery drug closely resembles other substances like fentanyl or cocaine, but its danger far exceeds that of nearly any other opioid on the street," the DEA wrote.

Its popularity in the illicit drug market is rising, the agency said, with most of the carfentanil seizures in 2024 being in a pill or tablet form.  

According to a  U.S. deaths with carfentanil detected increased approximately sevenfold, from 29 deaths in the first six months of 2023 to 238 during the same period in 2024.

The DEA noted that carfentanil has been found mixed with other drugs or pressed into pills that look like prescription painkillers, often to increase drug potency and profits. Users may be unaware they are consuming carfentanil.

Exposure to carfentanil can cause respiratory depression or arrest, drowsiness, disorientation, sedation, pinpoint pupils, and clammy skin. The onset of these symptoms usually occurs within minutes of exposure.

Treating or preventing a carfentanil overdose is difficult, as the antidote naloxone may not work in its normal doses, and fentanyl strips may not detect carfentanil.