Testing is Crucial in the Fight Against Xylazine

Aegis Clinical Pharmacist, Andrew Holt, Pharm.D., BCMAS, CPGx, has released an op-ed where he expresses the importance of clinical definitive testing for fentanyl-xylazine mixtures, an emerging threat to the United States.

On April 12, the Biden-Harris administration officially declared fentanyl-xylazine mixtures as an emerging threat to the United States. This followed a February announcement by the FDA outlining a plan to take measures to limit non-veterinary importation of xylazine. Both official designations are intended to reduce the growing threat of xylazine, and the troubling trend of overdose risks associated with fentanyl-xylazine mixtures.

Xylazine is a veterinary drug, appropriately used in animals as a sedative and muscle relaxant; but it is not approved for human use. It becomes a problem when it is used as an adulterant in the illicit drug supply, most often mixed with fentanyl, where it is believed to increase the effects of fentanyl. The combination can be deadly: The CDC reported that between 2020 and 2021 xylazine-positive overdose deaths increased by 1,127% in the South, 750% in the West, more than 500% in the Midwest, and more than 100% in the Northeast.

Although some effects of xylazine use are similar to opioids, chemically its actions do not take place at opioid receptors. This means naloxone, the medication often used to reverse fentanyl overdoses, does not reverse xylazine’s effects. In fact, one study found naloxone present in 33.3% of overdose deaths where xylazine was detected.1 Along with the drug’s central nervous system depressant activity, observational studies have also described occurrences of skin lesions that can progress to tissue necrosis if not cared for properly.2 Consequently, the health care community cannot solely focus on reactive or post-consumption treatments – we must be more proactive and look to curb the threat before it makes it to the end user.

How do you stop a threat that is hidden in plain sight like xylazine? A vital part of the administration’s plan is expanded testing for the drug. Select providers have had early access to xylazine testing since 2021, and the lab I work for, Aegis Sciences Corporation, was the first health care-specialized diagnostic laboratory to test for the drug. Testing is one of the only proven methods of identifying the drug and tracking its progress, in the hopes of stemming its spread.

However, keeping current with illicit drug trends is a difficult, time-consuming task, which requires a significant outlay of research and development capital. Allocating time to these endeavors requires significant commitment and belief from a laboratory’s leadership that enhanced testing affords providers the opportunity to save lives. In other words, not all testing is the same.

The emergence of illicitly manufactured fentanyl in 2013 was an early signal of the future of the illicit drug supply – a trend toward synthetically produced “designer drugs,” which has expanded to include fentanyl and nitazene analogs, along with designer benzodiazepines and other substances. As with xylazine, many of these substances can contribute to an individual’s overdose risk and evade routine drug tests.

Clinical laboratories can be crucial sources of information about illicit drug supply trends and utilization. As an ever-increasing portion of the illicit drug supply becomes synthetic in origin, the role of definitive testing becomes even more important to recognize. Clinical labs that provide enhanced, definitive testing can supplement the valiant efforts of forensic laboratories and early warning groups that educate government and public health officials about illicit drug trends, whether they be national or local in nature.

As with these traditional sources, data from clinical laboratories benefits the nation’s stakeholders involved in the reduction of overdose deaths through more informed harm-reduction measures. But most importantly, enhanced definitive testing provides crucial, potentially lifesaving tools and information to providers who are on the front lines of overdose prevention efforts. If we are serious about solving the crises of xylazine, fentanyl and designer drugs, then we must get serious about expanding access to testing nationwide.



1. Chhabra N, Mir M, Hua MJ, et al. Notes From the Field: Xylazine-Related Deaths – Cook County, Illinois, 2017–2021 [published correction appears in MMWR Morb Mortal Wkly Rep. 2022 May 06; 71(18):641]. MMWR Morb Mortal Wkly Rep. 2022; 71(13):503–504. Published 2022 Apr 1. doi:10.15585/mmwr.mm7113a3
2. Alexander RS, Canver BR, Sue KL, Morford KL. Xylazine and Overdoses: Trends, Concerns, and Recommendations. Am J Public Health. 2022;112(8):1212-1216. doi:10.2105/AJPH.2022.306881


Dr. Andrew Holt, Pharm.D., BCMAS, CPGx is a Clinical Pharmacist at Aegis Sciences Corporation.