A veterinary sedative used to immobilize large wild animals — including rhinoceroses, hence the street name "rhino tranq" — is now circulating in the American illicit fentanyl supply at a scale that has alarmed public health officials across the country. On April 2, 2026, the Centers for Disease Control and Prevention and the White House Office of National Drug Control Policy jointly issued a HAN Health Advisory warning clinicians, public health officials, harm reduction workers, and people at risk of overdose about the rapidly escalating presence of medetomidine in illegal drug samples, primarily in the Northeast and Midwest United States.
The advisory, classified as the most urgent type CDC issues — a Health Advisory rather than a mere Health Update — reflects the severity of what surveillance data show: medetomidine detections in illicit drug seizures rose from just 247 in 2023 to 2,616 in 2024 and then 8,233 in 2025. That is a greater than 3,000 percent increase in two years. By October 2025 through January 2026, medetomidine was being detected in treated wastewater every single week in at least one of 14 states enrolled in a national wastewater surveillance program. At eight sentinel drug testing sites, medetomidine was found in more than 50 percent of opioid-positive samples.
