Experts are warning that America’s opioid crisis is in its “fourth wave”, as a study published in the journal Addiction found that 32 per cent of all overdose deaths in 2021 resulted from a mixture of fentanyl with stimulants like cocaine or methamphetamine. The defining trait of this wave is the emergence of polysubstances – a combination of fentanyl with other drugs, like stimulants – driving overdoses. The chemical effect of the mixture heightens its danger: stimulants boost heart rate but opioids like fentanyl lower it. The combination of both makes the user more likely to overdose. The first wave started with the rise in prescription opioids during the early 2000s, the second with heroin in 2010 and the third with fentanyl’s emergence in 2013.
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