"Among the 42,249 opioid-related overdose deaths in 2016, 19,413 involved synthetic opioids, 17,087 involved prescription opioids, and 15,469 involved heroin. Synthetic opioid involvement in these deaths increased significantly from 3007 (14.3% of opioid-related deaths) in 2010 to 19,413 (45.9%) in 2016 (P for trend <.01). Significant increases in synthetic opioid involvement in overdose deaths involving prescription opioids, heroin, and all other illicit or psychotherapeutic drugs were found from 2010 through 2016 (Table).

"Among synthetic opioid–related overdose deaths in 2016, 79.7% involved another drug or alcohol. The most common co-involved substances were another opioid (47.9%), heroin (29.8%), cocaine (21.6%), prescription opioids (20.9%), benzodiazepines (17.0%), alcohol (11.1%), psychostimulants (5.4%), and antidepressants (5.2%) (Figure)."

Source

Jones CM, Einstein EB, Compton WM. Changes in Synthetic Opioid Involvement in Drug Overdose Deaths in the United States, 2010-2016. JAMA. 2018;319(17):1819–1821.