SF Records First Death Involving Animal Sedative Linked to Overdose Outbreaks in East

San Francisco reported its first death this year involving the powerful veterinary sedative medetomidine, which has been linked to a wave of fatal overdoses on the East Coast.

The victim, Jessica Monique Sheridan, 46, died in February, according to the San Francisco Office of the Chief Medical Examiner. The city health department confirmed that Sheridan’s toxicology report showed medetomidine in her system.

Other news outlets reported that Sheridan was found with a mix of drugs in her system, including fentanyl, medetomidine and benzodiazepines, which the Office of the Chief Medical Examiner did not confirm.

Among street drugs, medetomidine is most commonly detected as an adulterant in fentanyl mixtures. The synthetic depressant was first detected in California in 2023 and has been linked to several overdose outbreaks in states such as Pennsylvania and Illinois, according to a Center for Forensic Science Research & Education advisory.

When East Coast states began reporting an increased number of overdoses involving medetomidine last year, San Francisco Supervisor Matt Dorsey called on city public health officials to include the drug in the list of substances they test for during overdose and wastewater investigations.

The Department of Public Health said in a statement that it is tracking the presence of medetomidine in the city and preparing health and outreach workers to respond accordingly, but that it is not widespread. The overdose crisis is driven largely by fentanyl, which has been found in more than 70% of local overdose victims, the agency said.

Medetomidine is not the only novel synthetic drug to find its way to the West Coast. Xylazine, another veterinary sedative known as “tranq,” was involved in 62 overdose deaths in San Francisco last year. Fentanyl accounted for 83 deaths.

According to a study published in the journal ACS Chemical Neuroscience, medetomidine is over 100 times more potent than xylazine. Improper use of the drug is associated with severe blood pressure instability, including hypotension and central nervous system depression.

It’s too soon to say whether medetomidine will supplant other drugs in the illicit market even as its presence increases, said Keith Humphreys, a Stanford University professor and addiction policy researcher.

Both medetomidine and xylazine are earmarked for veterinary use and therefore face less rigorous regulation processes than substances made for humans, which could explain why they’re becoming more common in the recreational drug supply, Humphreys said.

What’s more important is making sure the public knows what the drug is and what its effects are, he continued.

Naloxone cannot be used to treat overdoses involving medetomidine. While there are reversal agents that can be used to reverse the drug’s sedative effects, they are not as common because they’re marketed for animals, Humphreys said.

San Francisco recorded 118 accidental drug overdose deaths in the first two months of 2025, according to preliminary data from the Office of the Chief Medical Examiner. The number of fatal overdoses this year — 57 in January and 61 in February — marks a significant uptick after four months of declines, with October seeing a low of 37.

Mayor Daniel Lurie and other city officials are pushing for more aggressive responses to the city’s unprecedented drug crisis.

Earlier this year, the Board of Supervisors passed Lurie’s ordinance titled “Fentanyl State of Emergency,” which gives the mayor’s office and other city agencies the authority to pursue city contracts and private donations to combat fentanyl use without supervisors’ approval.

Lurie also ordered the Public Health Department last month to scale back harm reduction programs that provide people with safe smoking supplies in public spaces, instructing health officials to move distribution indoors.

Humphreys said city officials need to consider more preventive measures when it comes to addressing drug abuse.

“If we continue to approach this problem by sort of waiting till people are engaged in really dangerous behavior and then throwing a lot of resources at them, we’ll never come to the end of this,” Humphreys said. “We need to have fewer people entering into that cycle of harm and risk because we can’t really control these markets and make them safe.”

KQED’s Gilare Zada contributed to this report.