A lethal dose in most people

 The vast majority of heroin used in the United States comes from Mexico, and fentanyl generally originates from sources in China. These drugs are trafficked into the United States through a variety of routes, including overland across the Southwest border, and through online orders that are shipped by international mail and express consignment services. Because these drugs originate almost exclusively from overseas, stopping these drugs from reaching the United States is a critical U.S. foreign policy priority. Taking advantage of the full set of diplomatic and international assistance tools, the State Department’s INL Bureau leads U.S. efforts to partner with foreign governments to reduce the availability of these illicit drugs and their precursor chemicals.