Federal health officials are raising concerns about a troubling new contaminant being found in the illegal drug supply.
The Centers for Disease Control and Prevention has issued a nationwide health advisory after detecting increasing levels of medetomidine, a veterinary sedative, in drugs that also contain fentanyl.
Medetomidine (sometimes referred to as “rhino tranq” or “dex”) is not approved for human use. It is typically used to sedate animals, including dogs. Health officials say its presence in street drugs is especially dangerous because it can cause profound sedation, slowed heart rate, and dangerously low blood pressure.
Even more concerning, the CDC warns that people exposed to the drug may experience severe withdrawal symptoms if use is stopped. Those symptoms can include high blood pressure, anxiety, nausea, vomiting, and changes in alertness, and in some cases requiring emergency or intensive care.
The drug has been increasingly detected in law enforcement seizures, drug samples, and even wastewater testing. From late 2025 into early 2026, it was found weekly in at least one of 14 states participating in national monitoring.
Because fentanyl is often involved, officials say overdose reversal drugs like naloxone should still be used in emergencies to restore breathing.
Health experts say the spread of medetomidine adds another unpredictable and dangerous layer to an already volatile drug supply.
