(NewsNation) — There’s a new warning in the fight against the opioid crisis.

The Drug Enforcement Administration says “rainbow” fentanyl is being distributed across the nation. The pills look like candy and have a powerful synthetic opioid that is 50 to 100 times more potent than morphine.

It’s the latest development in the U.S. opioid crisis, which claimed more than 57,000 lives in 2021. Fentanyl overdoses are becoming the leading cause of death in some cities, including Chicago.

Cook County Chief Medical Examiner Ponni Arunkumar said overdoses are now the most common cause of unnatural deaths in her office, even more than shootings or traffic accidents. 

“This is a synthetic opioid. And we’re seeing it a lot in these deaths is being mixed with other drugs, like heroin,” Arunkumar said. “More recently, we’re seeing it with drugs like cocaine and animal tranquilizer xylazine.”

More than 71,000 people died of fentanyl overdoses last year in the U.S., according to the Centers for Disease Control and Prevention, compared to nearly 30,000 in 2017. In Cook County, drug overdoses rose 200% from 2015 to 2021, Arunkumar said.

It’s a number that’s gone up so quickly that morgues in some cities are running out of space.

Cook County built a warehouse in 2020 to use as an overflow morgue for COVID-19 deaths. So far Arunkumar has not had to use it for fentanyl overdoses, but she said if something doesn’t happen soon it could become a reality. 

“The deaths we’re seeing are entirely preventable. Any small amount of fentanyl is deadly,” Arunkumar said. “The public needs to be aware of this deadly drug being mixed with other drugs.”