Opioid overdose happens when a toxic amount of an opioid—alone or mixed with other opioid(s),
drugs and/or substances—overwhelms the body’s ability to handle it.
Many opioid-related overdoses result from mixing prescription painkillers or heroin with benzodiazepines (benzos), cocaine and/or alcohol.
Fentanyl
Fentanyl is a synthetic opioid that is 50-100 times more potent than morphine, and 25-50 times more potent than heroin. Below are lethal doses of heroin, fentanyl, and carfentanil.
Drugs users are not always aware when their heroin is laced with fentanyl, so when they inject their usual quantity of heroin, they may accidentally take a deadly dose of the substance.