What is Xylazine?

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The Bottom Line

Xylazine, also known as "tranq," is a powerful animal tranquilizer. Although it is not intended for human use, xylazine is a common contaminant of illicit drugs in the United States. It may enhance the clinical effects of some drugs, worsening toxic effects. Xylazine use causes sleepiness and a slow respiratory rate, and may also result in development of necrotic skin wounds (skin wounds with dead tissue).

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What is xylazine ("tranq")?

Xylazine, also known as "tranq," is an animal tranquilizer used to induce sedation, pain relief, and muscle relaxation in dogs, cats, horses, and other veterinary species. Xylazine was initially studied in humans as a potential blood pressure-lowering drug, but its use in humans was abandoned after the drug was found to cause excessive sleepiness. Currently, xylazine is not approved by the United States Food and Drug Administration (FDA) for human use. Xylazine was initially discovered as an illicit drug contaminant in the United States in the early 2000’s. Since then, the United States Drug Enforcement Agency (DEA) has found xylazine in illicit drugs, including cocaine, heroin, and fentanyl, throughout the United States.

How is xylazine used?

Xylazine is available in liquid or powder formulations and can be consumed, inhaled, smoked, or injected. In one study, most deaths due to xylazine overdose were related to injection of the drug. Xylazine has also been used to facilitate sexual assault. In one case, a child collapsed after returning home from a nearby playground. He was taken to a hospital, where xylazine was detected in his blood and urine. A police investigation revealed that the child’s godfather had injected the boy with xylazine after he had returned from the playground. The godfather later admitted that he had intended to sexually assault the boy after poisoning him with xylazine.

What are the side effects of xylazine?

In humans, xylazine use can cause drowsiness, abnormally slow or absent breathing, low blood pressure, and a slow heart rate. In severe cases, coma may develop and require insertion of a breathing tube and hospitalization in an intensive care unit (ICU). The signs and symptoms of xylazine overdose are similar to those of heroin, fentanyl, and other opioids. When xylazine is combined with other opioids, severe toxicity and death may occur due to the combined effect of the drugs.

Does xylazine cause wounds?

Xylazine use causes blood vessel narrowing, which leads to decreased blood flow to the skin in areas where xylazine is injected. This can result in the formation of necrotic wounds, which are wounds with dead tissue, that can easily get infected due to poor circulation. Skin wounds due to xylazine injection are often managed with specialized dressings and antibiotics. Some wounds may require treatment with skin grafting or other surgical procedures, and severe cases may result in amputation.

Is xylazine a controlled substance?

In the United States, xylazine is not a controlled substance. It can be obtained, with a prescription, from veterinary pharmacies. Illicit formulations of liquid and powdered xylazine are available for purchase from online retailers for less than twenty dollars per kilogram, making the drug an attractive option for illicit drug manufacturers. Xylazine and other adulterants are added to illicit drugs to increase the bulk volume of the drug, raising profits for drug traffickers, and to enhance the “high” of the drugs.

Does xylazine cause withdrawal?

Withdrawal can occur in people who abruptly discontinue use of xylazine. Xylazine withdrawal can result in a markedly elevated blood pressure, a rapid heart rate, and agitation. Headaches, insomnia, and nausea may also occur during xylazine withdrawal. Individuals experiencing xylazine withdrawal may require hospitalization for treatment with medications that can reduce the severity of the withdrawal signs and symptoms.

Is xylazine zombifying?

Xylazine acts within the brain to cause sedation and abnormally slow breathing. The clinical effects of severe xylazine intoxication can last for several days. In some cases, affected individuals may appear to be in a trance-like state that people describe as being zombie-like.

Does Narcan reverse the effects of xylazine?

Naloxone (Narcan) is designed to reverse the effects of opioid drugs such as heroin, fentanyl, and oxycodone. Since xylazine is not an opioid, naloxone is unlikely to be effective in treating people who overdose on xylazine. However, since xylazine is a known contaminant of many illicit opioids, and because naloxone is unlikely to cause harm in individuals who have overdosed on xylazine, it is reasonable to administer a dose of naloxone in the event of a suspected xylazine overdose. Because overdose symptoms can recur after naloxone is given, it’s important to call 911 or seek emergency medical care as soon as possible after administering naloxone for a suspected opioid overdose.

What happens if someone gets sick after using xylazine?

If unwanted or unexpected symptoms develop after taking xylazine, contact Poison Control for expert advice. There are two ways to contact Poison Control in the United States: online at www.poison.org and by phone at 1-800-222-1222. Both options are free, confidential, and available 24 hours a day.

Kelly Johnson-Arbor, MD
Medical Toxicologist

Contact information for media requests.

For More Information

Tranq Dope: Animal Sedative Mixed With Fentanyl Brings Fresh Horror to U.S. Drug Zones (The New York Times)

Xylazine (Drug Enforcement Administration)

References

Andresen-Streichert H, Iwersen-Bergmann S, Mueller A, Anders S. Attempted Drug-facilitated Sexual Assault-Xylazine Intoxication in a Child. J Forensic Sci. 2017 Jan;62(1):270-273.

Ehrman-Dupre R, Kaigh C, Salzman M, Haroz R, Peterson LK, Schmidt R. Management of Xylazine Withdrawal in a Hospitalized Patient: A Case Report. J Addict Med. 2022 Sep-Oct 01;16(5):595-598.

Geyskes GG, Boer P, Dorhout Mees EJ. Clonidine withdrawal. Mechanism and frequency of rebound hypertension. Br J Clin Pharmacol. 1979 Jan;7(1):55-62.

Greene SA, Thurmon JC. Xylazine--a review of its pharmacology and use in veterinary medicine. J Vet Pharmacol Ther. 1988 Dec;11(4):295-313.

Malayala SV, Papudesi BN, Bobb R, Wimbush A. Xylazine-Induced Skin Ulcers in a Person Who Injects Drugs in Philadelphia, Pennsylvania, USA. Cureus. 2022 Aug 19;14(8):e28160.

Reyes JC, Negrón JL, Colón HM, Padilla AM, Millán MY, Matos TD, Robles RR. The emerging of xylazine as a new drug of abuse and its health consequences among drug users in Puerto Rico. J Urban Health. 2012 Jun;89(3):519-26.

Ruiz-Colón K, Chavez-Arias C, Díaz-Alcalá JE, Martínez MA. Xylazine intoxication in humans and its importance as an emerging adulterant in abused drugs: A comprehensive review of the literature. Forensic Sci Int. 2014 Jul;240:1-8.

Spoerke DG, Hall AH, Grimes MJ, Honea BN 3rd, Rumack BH. Human overdose with the veterinary tranquilizer xylazine. Am J Emerg Med. 1986 May;4(3):222-4.

Thangada S, Clinton HA, Ali S, Nunez J, Gill JR, Lawlor RF, Logan SB. Notes from the Field: Xylazine, a Veterinary Tranquilizer, Identified as an Emerging Novel Substance in Drug Overdose Deaths - Connecticut, 2019-2020. MMWR Morb Mortal Wkly Rep. 2021 Sep 17;70(37):1303-1304.

U.S. Department of Justice, Drug Enforcement Administration. The growing threat of xylazine and its mixture with illicit drugs. DEA Joint Intelligence Report. Available at https://www.dea.gov/documents/2022/2022-12/2022-12-21/growing-threat-xylazine-and-its-mixture-illicit-drugs. Accessed March 23, 2023.