Two deaths in Boulder County, Colorado, in 2023 are the latest in the United States attributed to a powerful class of synthetic opioids called nitazenes. Nitazenes are psychoactive substances or ‘designer drugs’ that are not controlled by any law or convention, but pose a significant risk to public health.

Most healthcare systems cannot detect these substances, so the exact number of overdoses is unknown, but they are known to be involved in more than 200 deaths in Europe and North America since 2019.