America’s fentanyl epidemic has become “even more unpredictable and lethal” as illegal drug producers shift to combining the highly addictive substance with synthetic opioids and sedatives, according to the U.S. government at the forefront of the 21st-century war on drugs.

The Drug Enforcement Administration issued an alert in mid-May of a new trend in how fentanyl was being introduced to U.S. consumers, both those seeking out fentanyl and unsuspecting users trying to buy other drugs. Fentanyl is increasingly being added to a variety of synthetic drugs, or artificially engineered, man-made chemicals, that are already powerful and potentially deadly.