Sept. 20, 2022: Fentanyl is now the leading cause of death in adults (ages 18-45) in the United States. The CDC reported that fentanyl comprises the largest cause by percentage of all drug overdose deaths with 37,208 fentanyl deaths for 2020 and 41,587 deaths for 2021–an almost 12% increase in one year–of the total deaths of 107,000 last year.