A man in his 40s overdosed on the synthetic opioid carfentanil, a drug 100 times stronger than fentanyl, Riverside County, California, health officials confirmed on July 17.

He was the first Riverside County resident confirmed to die from carfentanil.

The man, whom health officials did not name, died in March outside the county, but it took months to confirm the cause, health officials reported.

“Every life lost from opioids is one too many,” said county Public Health Officer Dr. Jennifer Chevinsky.

Carfentanil was developed for use as an elephant tranquilizer because of its potency. The drug is not approved for human use, according to the Drug Enforcement Administration (DEA).

Even a microscopic amount can cause a fatal overdose, Chevinsky said.

The DEA, a federal agency that enforces controlled substance laws and regulations, said that carfentanil stands out as one of the deadliest fentanyl varieties.

“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 stated. “Carfentanil is a chilling reminder of how the opioid epidemic continues to evolve and introduces new threats at an alarming pace.”

According to the Centers for Disease Control and Prevention (CDC), illegally manufactured carfentanil and other fentanyls entered the United States’ drug supply in 2013 as a substitute for white powder heroin in the northeast region of the country.

U.S. deaths from carfentanil increased from two in the first six months of 2023 to 14 during the same time in 2024, according to the CDC.

Illegally manufactured fentanyl was responsible for about 70 percent of the 105,000 overdose deaths in the United States in 2023, according to the agency.

An officer opens a printer ink bottle containing the opioid carfentanil imported from China, in Vancouver, Canada, on June 27, 2016. Drug dealers have been cutting carfentanil and its weaker cousin, fentanyl, into heroin to boost profit margins. (Royal Canadian Mounted Police via AP)

Carfentanil was found in 513 overdose deaths from January 2021 to June 2024, according to the CDC.

In April, a 39-year-old man in Northern California also died after overdosing on carfentanil. The counterfeit pills that he took, called M30, were made to resemble oxycodone but were laced with carfentanil, according to Santa Clara County’s medical examiner.

“Using drugs alone increases the risk of death,” said Dr. Michelle Jorden, chief medical examiner and neuropathologist in the county’s medical examiner’s office. “Fake pills look real, but they can be deadly. People should not take any pill that they did not buy from the pharmacy.”