A new scientific paper explains the recent drop in overdose deaths in the US by changes in the supply of fentanyl, particularly a decrease in its average potency. The authors refer to a "supply-side shock," that is, a sudden change in the quality or composition of available fentanyl on the black market. The analysis shows that overdose deaths began to decline from 2023 in parallel with the detection of lower concentrations of fentanyl in drug seizures. The study links this trend to changes in the production and distribution of fentanyl, which have led to less potent doses in drug mixes being used. Therefore, the authors do not attribute the decrease in deaths primarily to a decrease in the number of users, but to a change in the properties of the drug itself in the distribution chain. The main finding is that even without significant changes in the behavior of users, reducing the potency of a synthetic opioid can lead to a noticeable decrease in the number of fatal overdoses.