More than 80% of New Yorkers who inject drugs test positive for the opioid fentanyl, despite only 18% reporting using it intentionally, according to a new study.

The findings suggest that many people who inject drugs are unknowingly using fentanyl, which may increase their risk for overdose and potentially their tolerance to fentanyl if it is used over time.

In 2021, more than 100,000 people died of a drug overdose in the United States, with 66% of these deaths involving illicit the synthetic opioid that is 50 to 100 times more potent than morphine.

In New York City, drug overdose deaths have more than tripled since 2013 when fentanyl began to regularly appear in the illicit drug supply. Since 2017, fentanyl has been the most common drug involved in overdose deaths in New York City.

Research shows that people who take drugs may use the drug unintentionally, thinking that they are instead using heroin or another drug. However, more recent studies show that some people are aware of their use and may seek out fentanyl or heroin mixed with fentanyl.

“As the proportion of drug overdose deaths involving fentanyl continues to increase, it’s important to monitor how often people are exposed to fentanyl and any changes in preference for fentanyl among people who use drugs,” says Courtney McKnight, clinical assistant professor of epidemiology at New York University’s School of Global Public Health and lead author of the study in the International Journal of Drug Policy.

To understand the pervasiveness of fentanyl use in New York City, McKnight and her colleagues conducted surveys and in-depth interviews in 2021 and 2022 with people who inject drugs. In the 313 surveys and 162 interviews, the researchers asked participants about their drug use, including whether they used fentanyl intentionally in the last month, and their experience with overdoses.

Read the full article about fentanyl by Rachel Harrison at Futurity.