Iso is a relatively recent addition to the U.S. opioid crisis. While it is primarily manufactured in China and was originally popular across central Europe, it is now becoming more widespread in several American states, including Illinois. In the past year, iso was identified in the bloodstream of several Illinoians who died from an overdose.
Isotonitazene has been linked to increased numbers of deaths caused by opioid overdose. This effect is largely due to the fact that iso is highly potent yet legal across most of the country.