The New Deadliest Drug in the World There’s a new killer in town, and the results are astonishing. Just 2 milligrams of this substance can kill you. A pinch of the synthetic opioid Fentanyl is enough to cause a deadly overdose. Frequently, dealers have been cutting heroin with fentanyl to intensify the potency of the drug.  The deadly drug fentanyl is a powerful synthetic opioid that is like morphine but is 50 to 100 times more potent. Its comes in many forms such as intravenous fentanyl, powered fentanyl, and pill…