The percentage of overdose deaths from fentanyl combined with stimulants like cocaine and methamphetamine increased 50-fold between 2010 and 2021, according to a new analysis done by researchers at the University of California. Many people who use drugs like cocaine recreationally may not be aware these drugs are laced with fentanyl, a powerful opioid that can be deadly in small doses. This could be fueling unintentional overdoses, according to experts.

Deaths from stimulants laced with fentanyl represents the “fourth wave” of the U.S. overdose crisis, according to the research team behind the new study. “We think of it like waves, and with the first wave being prescription opioids, the second wave being heroin, the third wave being fentanyl and this fourth wave is fentanyl with stimulants. To read the full story.