Xylazine is a non-opioid sedative commonly used for procedural sedation in veterinary medicine. Xylazine is in a class of medications called alpha-2 adrenergic agonists. This means it is not an opioid, but instead is more chemically similar to other sedative medications that decrease activity and have a calming, relaxing effect such as clonidine (an antihypertensive medication). Xylazine was never approved by the U.S. Food and Drug Administration (FDA) for use in humans because in clinical trials it caused severe central nervous system (CNS) depression or sedation in humans.
Xylazine is seen primarily as an additive in the unregulated drug supply and is not typically a substance that is used on its own. Although it has been found to be mixed in with other substances, xylazine most commonly is being added to illicitly manufactured fentanyl. Xylazine is described as giving fentanyl ‘legs’ meaning it may extend the duration of effect that fentanyl has in persons using it. Because xylazine is an additive in the unregulated drug supply, people who use drugs (PWUD) may be using xylazine knowingly or unknowingly. Qualitative research has shown that PWUD have mixed preferences for xylazine, although most PWUD try to avoid using it because of the potential negative health impacts it causes.
Common names for xylazine:
• Tranq
• tranq dope
• anestesia de caballo
• Rompun (veterinary medication brand name)
• AnaSed (veterinary medication brand name)
Where does xylazine come from?
Because xylazine is used commonly in veterinary medicine, it is suspected it is diverted from veterinary sources. Xylazine was first seen as an additive in the unregulated drug supply in Puerto Rico in the early 2000s and began appearing in Philadelphia soon thereafter. Since then, xylazine has spread within the Northeast and continued to spread westward and southward. It is unknown how, when, and where in the unregulated drug supply chain xylazine is being added
What are the effects of xylazine?
Sedation: Xylazine causes deep sedation and a heavy nod, especially in the first 20-30 minutes after use, depending on the route of administration. When using substances containing xylazine, a person can be sedated deeply for several hours. This can put them at risk for physical and sexual assault, theft, and medical complications from lying in one position for too long.
These medical complications can include:
- Pressure ulcers
- Blood clots
- Compartment syndrome: a painful condition where the pressure in and around muscles rises to dangerous levels
- Rhabdomyolysis: a serious medical condition that occurs when muscle tissue breaks down potentially damaging the liver and kidneys
Central nervous system depression: Xylazine causes severe CNS depression in humans which can contribute to muscle relaxation of the tongue which can block the airway and prevent a person from breathing.
Potential Health Impacts of Xylazine:
- Overdose: When using substances that contain both fentanyl and xylazine there is an increased risk for overdose because of the combination of the sedation and CNS depression caused by xylazine coupled with the respiratory depression caused by opioids.
- Physical dependence and withdrawal: While there isn’t yet a defined use disorder associated with xylazine, the unintentional or intentional use of xylazine can contribute to physical dependence and withdrawal symptoms can occur when someone decreases or stops using xylazine. Symptoms of withdrawal may include non-specific anxiety, high blood pressure, increased heart rate, sweating, restlessness, agitation and irritability.
There are not yet clear recommendations on clinical treatment for xylazine withdrawal; however, case reports suggest there are benefits to using other alpha-2 agonists like clonidine for managing xylazine withdrawal symptoms.
- Skin wounds: Xylazine use can lead to the development of skin wounds. These wounds can occur in both persons who inject and in persons who do not inject substances. For those who do inject substances, the wounds can occur at the injection site or in places where the person has not injected. Currently, it is unknown why these skin wounds occur both with and without injection use.
