Above is an Upset plot (similar to a Venn Diagram but with numbers) showing all samples positive for xylazine over the course of this study. So far, xylazine always co-occurs with fentanyl and its associated compounds, tentatively suggesting xylazine is an adulterant of illicitly manufactured fentanyl in San Francisco. This fits with national trends, where xylazine has been added to the opioid supply but not to other classes of drugs

Above is an Upset plot (similar to a Venn Diagram but with numbers) showing all samples positive for fentanyl or one of its metabolites, and the co-occurrence of fentanyl analogs. So far in this study, fentanyl analogs have only been detected in samples where fentanyl or a fentanyl metabolite are also detected. This tentatively suggests fentanyl analogs co-occur with fentanyl in the drug supply, rather than being an independently manufactured and marketed drug