The spread of illegally manufactured opioids, including fentanyl, has brought unprecedented levels of drug overdose deaths in North America. In some markets, illegally manufactured fentanyl (IMF) is essentially displacing heroin, not just being used to adulterate it. It is not possible at this time to provide an accurate point estimate of the amount of IMF consumed in the United States. Yet for various purposes (e.g. assessing changes in production levels and the appropriate role for various supply reduction efforts), it is important to have a sense of scale. This article provides guidance through two thought experiments that provide a hypothetical upper bound on U.S. consumption. The first considers a scenario in which IMF replaces heroin in all illegal opioid markets. The second starts with the number of individuals with an opioid use disorder and considers what total consumption would be if IMF was the only opioid they consumed. Both calculations suggest it is unlikely that the annual consumption of IMF in 2021 could have been more than single digit pure metric tons. For comparison, the most recent best estimates of the amount of cocaine and heroin consumed in the U.S. are 145 and 47 pure metric tons, respectively. The article also raises questions about the limitations of using traditional equianalgesic morphine equivalent dose conversions to estimate the total market consumption of IMF.
