Boston – The Drug Enforcement Administration is warning the public of dangerous and deadly counterfeit prescription pills that have infiltrated the black market in the U.S.

According to the DEA, drug cartels from Mexico are manufacturing mass quantities of these pills, which are laced with fentanyl – which can be deadly, even in very small doses. Based on a sampling of pills that were seized by the agency earlier this year, 27% contained potentially lethal doses of the drug. The agency says these type of counterfeit pills are responsible for thousands of opioid-related deaths each year in the U.S.