# Examination of Xylazine Exposure and the Risk of Skin and Soft Tissue Infections in People Who Inject Drugs

> **NIH NIH R21** · TUFTS UNIVERSITY BOSTON · 2024 · $453,750

## Abstract

Summary
Alterations in the availability, potency, or composition of illicit drugs can lead to shifts in drug use behaviors and
drug-related morbidity and mortality. Such changes can expose individuals to new risks, potentially increasing
the likelihood of infection. In recent years, Xylazine, also known as "tranq" or "tranq dope" or "anestesia de
caballo," has significantly affected people who inject drugs (PWID). Xylazine, a phenothiazine, induces sedation,
giving users a false perception of prolonged fentanyl effects. Xylazine has several adverse effects, including
severe infections, skin ulceration, and prolonged sedation. However, little is known about how xylazine
contributes to increased rates of severe skin and soft tissue infections (SSTI) among PWID. The possible
explanations are allergic reactions to drug adulterants and other drug excipients or xylazine-driven
vasoconstriction leading to decreased blood flow into the tissue leading to necrosis followed by skin infections.
While there is a strong understanding of factors that are protective against SSTI, additional research is needed
to understand if harm reduction measures such as use of clean syringes, good hygiene and stable housing are
protective in the context of xylazine exposure. Additional challenges exist in measuring the exposure to xylazine.
While tests that can identify xylazine and its metabolites in urine, drug paraphernalia, and drug samples, a single
test cannot provide an accurate estimate of xylazine exposure as the drug supply is constantly changing.
Therefore, there is a critical need to develop testing regimens to assess time varying exposures to xylazine and
to then use the exposure data to better assess associations between xylazine exposure and SSTI incidence. We
propose to prospectively recruit 200 PWID from Lowell, Massachusetts and follow them for a period of three
months, quantifying exposure to xylazine and other drugs and measuring the incidence of SSTI. We will examine
xylazine exposure among PWID using a combination of laboratory assessment, xylazine test strips, and urine
analysis at multiple timepoints. We will then examine the incidence of SSTI among PWID in the study and
determine the increased risk associated with xylazine use. In addition, we will use a qualitative research
framework interviewing 15 PWID who develop SSTI and additional 15 PWID who do not develop SSTI to better
understand the context surrounding SSTI risk factors and manifestations, as well as PWID healthcare interests,
experiences, and challenges following SSTI. Our proposed mixed methods study will help identify the best
assessments of exposure to xylazine and more precise associations between xylazine exposure and SSTI
incidence, while also elucidating moderating and mediating risk factors.

## Key facts

- **NIH application ID:** 10975748
- **Project number:** 1R21DA061423-01
- **Recipient organization:** TUFTS UNIVERSITY BOSTON
- **Principal Investigator:** Thomas J Stopka
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $453,750
- **Award type:** 1
- **Project period:** 2024-09-15 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10975748

## Citation

> US National Institutes of Health, RePORTER application 10975748, Examination of Xylazine Exposure and the Risk of Skin and Soft Tissue Infections in People Who Inject Drugs (1R21DA061423-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10975748. Licensed CC0.

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