Xylazine is used as a sedative for various animal breeds. Despite its approved and legal use for animals, people have started experimenting with the drug. It is known on the street as “horse tranquilizer” or “zombie drug.”

In June 2012, the Journal of Urban Healthpublished a paper that explored how veterinary medications are becoming more popular for recreational use. Forensic Science International also released a similar paper about this topic in 2014.

Although the drug is powerful, its appeal for recreational use is that xylazine is not regulated. This means people are technically not breaking the law if they possess this substance, depending on where they live.

Medical Uses

Xylazine is meant for medical use in animals only, according to ScienceDirect. Veterinarians use this medication as a sedative in different doses, depending on the animal they are treating. Xylazine is also used with ketamine before surgery.

In Animals, Some Side Effects of Xylazine Use are:

  • Reduction in cardiovascular performance
  • Slower heart rate (bradycardia)
  • Decrease in blood pressure (hypotension)

Veterinarians often use atipamezole to reverse the sedative effects of xylazine after an animal receives surgery. The use of xylazine for humans is not approved by the FDA, according to the Journal of Urban Health.

Scientists are just now examining why people use it for recreational reasons and how it can harm them.

Dangers of Human Use of Xylazine

The Journal of Urban Health mentions that in humans, xylazine can cause effects that are similar to opioids such as heroin. Though the case study published looked at xylazine use in Puerto Rico, the small sample found that people often used xylazine for the following reasons:

  • It is used as an adulterant along with drugs like cocaine and heroin or a combination of these two drugs (speedball).
  • Xylazine users are aware that it is not currently regulated by the FDA.
  • Heroin users sometimes use xylazine without knowing this because they buy heroin expecting it to be pure, but xylazine may be an active ingredient that has been added or mixed into it.
  • However, many heroin users knew that a new heroin supply was available that had been cut with xylazine.

The case study shows that in Puerto Rico, the use of xylazine has been documented in the medical community and linked to several deaths.

Short-Term Consequences of Using Heroin Laced with Xylazine, as Mentioned in the Case Report, Are:

  • Sleeping more after injection use
  • Changes in the scent of breath, feces, and urine
  • Increase in ulcers and injuries to the skin at injection sites, including abscesses

In Puerto Rico, heroin users also mentioned that it was getting hard to find heroin that does not contain xylazine.

Long-term consequences of xylazine use (either alone or with heroin) still need to be studied. However, a case study from the Journal of Urban Health mentioned that 21.1 percent of people in their sample reported overdoses on heroin that was cut with xylazine.

In addition, people who use heroin or speedball that has been cut with xylazine are at higher risk of skin lesions than people who use heroin on its own.

Some of these overdoses have been linked to deaths. In 2014, Forensic Science International found that xylazine can be toxic to humans when used on its own, and combining this substance with heroin could lead to death because both drugs have toxic effects on people.

Statistics of Use in the United States

Most studies conducted on xylazine misuse have been done in Puerto Rico. However, the National Institute on Drug Abuse (NIDA) mentions that misuse is a concern around the world.

Users of Xylazine Worldwide Often Take it Along with Heroin. Study Samples From the Journal of Urban Health Show the Following Demographic Breakdown:

  • Men are more likely to use xylazine and mix it with a speedball.
  • Users between 24 and 34 years old represent the majority of those who use xylazine, at 45.9 percent.
  • People who have used drugs for 10 to 15 years are more likely to use xylazine and represent 40.7 percent of users in the case study.

Does Xylazine Result in Tolerance?

Research for xylazine does not mention tolerance in humans or animals. NIDA  reports that people do use xylazine (alone or with heroin) on a consistent basis.

The 2014 abstract published shows that people who use xylazine often suffer from skin lesions, and this points to the fact users frequently make a habit of using xylazine. This also indicates the possibility of tolerance that needs to be researched.

Using an animal drug to get around the law demonstrates problematic behavior around drugs and signifies misuse. NIDA states that addiction is a complex disease of the brain, indicated by this kind of misuse.

Treatment for Misuse

The National Institute on Drug Abuse points out that no one profile can describe a drug addict. Put simply; anyone can misuse a substance. Even though xylazine is not yet scheduled, a drug does not need to be explicitly illegal in order for people to seek treatment for its misuse.

The science of addiction as we know it today explains that it takes more than willpower and a desire to quit drugs to recover successfully.

NIDA mentions that misuse of any drug involves cravings and use despite harmful consequences, and this is often the result of not being able to control urges to use. However, drugs can change the brain and cause the person to seek drugs even when a substance is having a negative, visible impact on their life.

Treatment for xylazine misuse can include:

Long-Term Care

People may require access to care on an as-needed basis if relapse occurs.

Individualized Care

Treatment needs to be tailored to the person’s needs and circumstances.


Comprehensive therapy increases a person’s chances of successfully recovering.

Withdrawal Management

Detox from a problem substance is vital, but it is only the first step toward recovery

Medical Supervision

Medical assistance may be necessary for a person to fully address misuse.

At the moment, more research needs to be conducted on how xylazine is used in humans. There is still much that is not understood about how it affects and harms humans.

Any use of xylazine is a clear sign of abuse, and help is needed to address this.

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