The CDC has issued a national health advisory warning that medetomidine — a veterinary sedative not approved for human use — is increasingly being detected in the illicit fentanyl supply, raising the risk of overdose and severe withdrawal syndrome.
The agency, in coordination with the White House Office of National Drug Control Policy, said the drug has been identified in law enforcement seizures, clinical samples and wastewater, with the highest concentrations in the Northeast, according to the April 2 alert. Reports of medetomidine in drug seizures rose 950% from 247 in 2023 to 2,616 in 2024, then climbed a further 215% to 8,233 in 2025.
Testing data show the drug is frequently copresent with fentanyl. From July through December 2025, medetomidine was detected in nearly 35% of opioid-positive samples across 10 of 20 surveillance sites, and 98% of medetomidine-positive samples also contained fentanyl.
The agency is urging clinicians to watch for prolonged sedation and severe withdrawal symptoms that may require ICU-level care. In one Chicago cluster, 12 confirmed, 26 probable and 140 suspected cases were reported, with at least 16 hospitalizations and one death.
The CDC said the evolving drug supply underscores the need for toxicology testing and coordination across healthcare and public health systems to identify and respond to emerging threats.
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