In most cases xylazine is mixed with strong opioids, such as heroin or fentanyl, which is a common combination in the United States. However, xylazine was also detected in the absence of strong opioids alongside stimulant drugs such as cocaine, and found in items sold as counterfeit codeine and diazepam (Valium) tablets and even THC vapes. 

Researchers warn the wider population of people who use drugs beyond heroin users will be exposed to xylazine's harms. 

The findings come after the team from the National Programme for Substance Abuse Deaths (NPSAD) at King's College London reported on the death of a 43-year-old man from Solihull, West Midlands, in May 2022. This is the first death outside North America and the first in the UK to be linked to xylazine use. 

Xylazine is a non-opioid sedative, painkiller and muscle relaxant used in veterinary medicine as a tranquiliser for animals. The drug – known as ‘tranq’ or ‘tranq dope’ when cut with heroin and fentanyl – is causing widespread problems in United States, as it can dangerously lower breathing and heart rate. If injected directly into the user’s bloodstream this reduces the need to re-dose, but this can cause large open skin ulcers to form. 

Researchers contacted all toxicology laboratories in the UK to collate evidence of xylazine detections in biological samples. They found the presence of the drug in sixteen people –. eleven samples were from Summer 2023 alone. 

Read the University of Bristol news item

Paper: 'Broad evidence of xylazine in the UK illicit drug market beyond heroin supplies: triangulating from toxicology, drug testing, and law enforcement' by Caroline S. Copeland et al. in Addiction [open access]