Objective:

To analyze the prevalence and concentration of xylazine in fentanyl-positive urine drug tests (UDT) across the United States.

Approach:

• Study Design: A national retrospective cross-sectional analysis of 42,307 fentanyl-positive UDT specimens tested for xylazine.
• Data Collection: Specimens were collected from March 2023 to September 2025 from patients aged 18 and older across various clinical settings.
• Statistical Analysis: Descriptive statistics and multivariable logistic regression models were used to assess xylazine detection and concentration.

Key Findings:

• Only 16.91% of specimens tested positive for xylazine, which is lower than the proportion reported in a 2025 xylazine prevalence study.
• Monthly xylazine concentrations peaked in 2023 and subsequently declined, despite an overall increase in xylazine copositivity.
• Xylazine copositivity with fentanyl increased more significantly in Western US regions compared to Eastern regions.

Interpretation:

Xylazine co-occurrence with fentanyl is not limited to the Northeast, indicating a broader public health concern.

Limitations:

• The study population primarily consisted of patients from substance use treatment settings, potentially excluding uninsured individuals.
• Regional variations in copositivity rates may reflect clinician ordering practices rather than actual differences in drug supply.

Conclusion:

The findings highlight the need for increased clinical awareness and testing for xylazine in patients with fentanyl-positive UDT results.

Sources:

• Sugarman et al. Study