On the left, a lethal dose of heroin; on the right, a lethal dose of fentanyl. (Photo from New Hampshire State Police Forensic Lab)
Drugs users generally don’t know when their heroin is laced with fentanyl, so when they inject their usual quantity of heroin, they can inadvertently take a deadly dose of the substance. In addition, while dealers try to include fentanyl to improve potency, their measuring equipment usually isn’t fine-tuned enough to ensure they stay below the levels that could cause users to overdose.
