ArticleDrug and alcohol dependence reports2025
Xylazine prevalence and concentration in the Los Angeles fentanyl market, 2023-2025.
Article in Drug and alcohol dependence reports, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
7 citing papers in PubMed.
- New trends in the overdose epidemic: postural impact on abusers of fentanyl and xylazine and clinical and forensic implications.Forensic science, medicine, and pathology · 2026Review
- Xylazine-Fentanyl Positivity and Concentration in Urine Drug Tests.JAMA network open · 2026Article
- Estimating the Daily Milligrams of Morphine Equivalent of Illicit Fentanyl Use in Los Angeles: Clinical and Epidemiological Implications.medRxiv : the preprint server for health sciences · 2026Article
- Xylazine exacerbates fentanyl-induced respiratory depression and prevents rescue by naloxone in mice.Psychopharmacology · 2026Article
- Assessing the real-world performance of xylazine test strips for community-based drug checking in Los Angeles.Harm reduction journal · 2026Article
- High variation in purity of consumer-level illicit fentanyl samples in Los Angeles, September 2023-April 2025.The International journal on drug policy · 2025Article
- Recent advances in the identification and quantification of xylazine and medetomidine in biological specimens.Bioanalysis · 2025Review
Corrections and comments
- Update of
Authors and funding
11 authors.
Funding
Abstract
Background: The veterinary sedative xylazine has been mostly described on the East Coast-yet early reports indicate that it is now arriving to West Coast fentanyl markets. Emerging drug checking approaches can provide information about the concentration and prevalence of xylazine in illicit fentanyl. Methods: Fentanyl samples from a community-based drug checking program in Los Angeles, California were assessed using direct analysis in real time mass spectrometry (DART-MS). A subset was analyzed with liquid chromatography-mass spectrometry (LC-MS) to quantify the concentration of xylazine, fentanyl, and other compounds. Results: Among n = 536 fentanyl-positive samples, n = 103 were xylazine-positive, and n = 78 had quantitative results available. Xylazine positivity rose from 0 % in 2023 quarter 1 to a peak of 29.5 % in 2025 quarter 1. A significant time trend was observed (OR per quarter year= 1.35 [95 %CI: 1.19-1.52]). Xylazine concentration in fentanyl samples was generally low, with a highly skewed distribution (mean=2.42 %, sd=7.80 %). 76.9 % of xylazine-positive samples had <1.0 % xylazine concentration. Compared to xylazine-negative samples, xylazine-positive samples were more likely to contain bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (BTMPS) [46.60 % vs 17.30 %], and lidocaine (65.0 % vs 29.6 %), and had lower average fentanyl concentration (6.12 % vs 10.7 %). Conclusions: We note increasing xylazine positivity among samples of illicit fentanyl in Los Angeles, California. The distribution of xylazine concentration is highly skewed, with a small number of very high concentration samples, and majority with <1 %. Nevertheless, more research is needed to study the health impacts of even the low concentration xylazine that is most predominant here; the average participant may still be exposed to a physiologically significant dose of xylazine.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.