The illicit fentanyl supply is changing again.
For several years, public health officials have warned about xylazine, commonly called “tranq,” appearing alongside fentanyl. Now another powerful veterinary sedative is becoming increasingly important: medetomidine, sometimes called “rhino tranq,” “mede,” or “dex.”
Medetomidine has already been identified in the illicit fentanyl supply in several Kentucky counties, making this an emerging concern for people who use opioids and their families throughout Lexington and the Commonwealth.
Unlike fentanyl, medetomidine is not an opioid. It can cause profound sedation, dangerously slow heart rate and low blood pressure. Repeated exposure may also result in a potentially severe withdrawal syndrome.
One of the biggest concerns is that people may not intentionally use medetomidine at all. It can be mixed into illicit fentanyl, which means someone may be exposed without knowing it.
As Kentucky’s drug supply evolves, understanding rhino tranq, how medetomidine differs from xylazine, whether Narcan works during an overdose and what unusual withdrawal symptoms may look like is becoming increasingly important.
“Rhino tranq” is an emerging name for medetomidine, a powerful alpha-2 adrenergic agonist used as a veterinary sedative.
The Centers for Disease Control and Prevention (CDC) reports that medetomidine is not approved for use in people and is increasingly being detected in the illegal drug supply, primarily alongside illegally manufactured fentanyl.
Names associated with medetomidine may include:
Medetomidine should not be confused with xylazine. Although both are non-opioid veterinary sedatives that have appeared in fentanyl, they are different drugs.
In April 2026, the CDC issued a national health advisory warning about increasing medetomidine detections and the potential for overdose complications and severe withdrawal.
The increase has been rapid. Federal data show that law-enforcement reports involving medetomidine increased from 247 in 2023 to 2,616 in 2024 and 8,233 in 2025.
For people who use fentanyl, the emergence of another potent sedative creates an additional risk: the substance someone purchases may contain drugs they did not intend to take.
Medetomidine is increasingly being detected as part of the illicit opioid supply, particularly alongside fentanyl.
That does not necessarily mean people are deliberately seeking rhino tranq.
Instead, someone purchasing what they believe is fentanyl may unknowingly consume medetomidine, xylazine or other substances contained in the same product.
This is part of a larger change in the illicit opioid market.
Fentanyl itself dramatically increased overdose risk because of its potency. The emergence of xylazine introduced a powerful non-opioid sedative into portions of the fentanyl supply. Medetomidine is now adding another layer of uncertainty.
CDC-supported surveillance during the second half of 2025 found medetomidine in opioid-positive samples across several regions of the United States.
Among participating sentinel sites, approximately 74% of opioid-positive samples in the Northeast contained medetomidine, compared with 56% in the Midwest and 30% in the South.
Those numbers should not be interpreted as the prevalence of medetomidine in every community. They do, however, demonstrate how widely the substance has spread.
Yes. Medetomidine has been detected in Kentucky.
Public health information from the University of Kentucky reports that medetomidine has been identified in the illicit fentanyl supply in several Kentucky counties.
This is particularly important for people in Lexington and throughout Central Kentucky because it demonstrates that rhino tranq is not exclusively a Philadelphia or Northeastern drug trend.
It has reached Kentucky’s illicit opioid supply.
That does not mean every fentanyl sample in Lexington contains medetomidine. The illicit drug supply can differ significantly between cities and even between individual batches sold in the same community.
The larger concern is unpredictability.
Someone may use what they believe is the same substance they previously consumed but encounter a different combination of fentanyl, medetomidine, xylazine or other drugs.
For someone already dependent on fentanyl, that uncertainty can affect both overdose risk and withdrawal.
Medetomidine, xylazine and fentanyl are sometimes discussed together, but they are not the same type of drug.
The most important distinction is that fentanyl is an opioid, while medetomidine and xylazine are not.
|
Medetomidine / Rhino Tranq |
Xylazine / Tranq |
Fentanyl |
|
|
Drug type |
Alpha-2 agonist sedative |
Alpha-2 agonist sedative |
Synthetic opioid |
|
Opioid? |
No |
No |
Yes |
|
Naloxone directly reverses it? |
No |
No |
Yes |
|
Can appear with illicit fentanyl? |
Yes |
Yes |
N/A |
|
Major concerns |
Profound sedation, slow heart rate, low blood pressure, severe withdrawal |
Sedation, wounds and cardiovascular effects |
Respiratory depression and fatal overdose |
These differences are particularly important during an overdose.
Naloxone can reverse fentanyl because fentanyl is an opioid. It does not directly reverse medetomidine or xylazine.
That means someone exposed to multiple substances may continue experiencing significant sedation even after receiving naloxone.
There is evidence of this happening in some local drug markets, but it would be inaccurate to say medetomidine has replaced xylazine nationwide.
The clearest example comes from Philadelphia.
CDC researchers found that medetomidine replaced xylazine as the most common adulterant in Philadelphia’s illicit opioid supply during the final four months of 2024.
That was a significant change because Philadelphia had previously become one of the country’s most prominent examples of fentanyl mixed with xylazine.
The finding demonstrates how quickly illicit drug supplies can evolve.
It does not establish that the same transition has occurred in Lexington or throughout Kentucky.
Xylazine remains a concern, and some illicit drug samples may contain multiple substances at the same time.
For people using fentanyl, the practical concern is therefore less about whether medetomidine has officially “replaced” xylazine and more about how difficult it has become to know what a particular batch contains.
“Dex” is one of the names federal health officials have associated with medetomidine.
The nickname may relate to dexmedetomidine, one of medetomidine’s two isomers.
Dexmedetomidine has legitimate medical uses when administered in controlled healthcare environments. Medetomidine itself is used as a veterinary sedative and is not approved for human use.
Street names should not be treated as reliable chemical identification.
Terms such as “dex,” “mede,” “tranq” and “rhino tranq” may be used differently from one community to another. The contents of an illicit substance cannot be reliably determined by its name, appearance, packaging or previous experience with the same supplier.
Medetomidine affects the central nervous system and cardiovascular system.
According to the CDC, exposure may cause profound and sometimes prolonged sedation, significantly slowed heart rate and low blood pressure.
Potential effects include:
These effects can become especially dangerous when medetomidine is combined with fentanyl.
Fentanyl can suppress breathing and cause a fatal opioid overdose. At the same time, medetomidine can contribute significant sedation and cardiovascular instability.
This combination can also make an overdose look different from an opioid overdose involving fentanyl alone.
Naloxone, commonly known by the brand name Narcan, does not directly reverse medetomidine.
Medetomidine is not an opioid.
However, that does not mean naloxone should be withheld during a suspected overdose.
Because medetomidine is frequently detected alongside fentanyl, naloxone should still be administered whenever an opioid overdose is suspected. Naloxone can reverse fentanyl’s opioid effects even when medetomidine continues affecting the body.
The distinction is important:
Narcan can reverse the fentanyl component of an overdose, but it cannot directly reverse rhino tranq.
Someone may therefore remain heavily sedated after receiving naloxone.
If a person cannot be awakened, is experiencing breathing problems or appears to be overdosing, call 911 and administer naloxone if available.
Persistent sedation after naloxone requires emergency medical evaluation.
People familiar with opioid overdose sometimes expect someone to rapidly wake up after naloxone.
Today’s polysubstance drug supply can make the response more complicated.
If fentanyl and medetomidine are both present, naloxone may reverse the fentanyl while medetomidine continues causing:
Continued sedation does not necessarily mean naloxone failed.
It can indicate that another substance is contributing to the overdose.
Emergency medical care remains important even when someone initially responds to naloxone.
Withdrawal has become one of the most concerning aspects of medetomidine exposure.
Repeated exposure may lead to physical dependence, including among people who did not know medetomidine was present in the fentanyl they were using.
Reported medetomidine withdrawal symptoms include:
These symptoms can involve significant disruption of the autonomic nervous system, which helps regulate functions such as heart rate and blood pressure.
Severe cases may require hospital treatment.
Someone who regularly uses fentanyl may have experienced opioid withdrawal before and believe they know what to expect when they stop.
Medetomidine can change that experience.
Between September 2024 and January 2025, clinicians at three Philadelphia health systems identified 165 hospitalized patients experiencing fentanyl withdrawal complicated by symptoms consistent with medetomidine withdrawal.
Some patients developed severe hypertension and rapid heart rate. Researchers also reported that the syndrome did not respond as expected to medications previously used for fentanyl and xylazine withdrawal.
The findings have an important implication for people who regularly use illicit fentanyl:
The withdrawal they experience may not come from fentanyl alone.
Repeated exposure to medetomidine, xylazine or other substances may complicate symptoms.
This is one reason unusually severe withdrawal should be professionally evaluated.
Not every person stopping fentanyl will experience severe medetomidine withdrawal. However, certain symptoms should not be assumed to be routine opioid withdrawal.
Seek urgent medical care for symptoms such as:
Someone experiencing a medical emergency should call 911 or go to the nearest emergency department.
For people who are not experiencing an immediate emergency but have become dependent on fentanyl or other opioids, an addiction-treatment assessment can help determine the safest and most appropriate next step.
Medetomidine highlights a larger change in America’s drug supply.
A person may identify fentanyl as their primary substance but actually be exposed to several drugs.
One batch might contain fentanyl and xylazine. Another might contain fentanyl and medetomidine. Other substances may also be present.
This means a person can potentially develop complicated patterns of exposure without intentionally choosing every drug involved.
Polysubstance exposure can affect:
Effective addiction treatment therefore needs to look beyond the name of someone’s primary drug.
A comprehensive assessment considers what the person is using, how often they are using, previous withdrawal experiences, overdose history, physical health, mental health and other factors that influence treatment needs.
A suspected overdose involving fentanyl, medetomidine or an unknown combination of substances is a medical emergency.
Call 911 immediately and administer naloxone if available.
Follow instructions from emergency dispatchers. Monitor the person’s breathing and responsiveness and provide rescue breathing or CPR if trained and instructed to do so.
Stay with the person until emergency medical professionals arrive.
Do not assume the person is safe because naloxone has already been administered.
If medetomidine, xylazine or another non-opioid sedative is involved, significant sedation may continue after fentanyl’s opioid effects have been reversed.
Knowing that fentanyl may contain medetomidine does not make opioid dependence disappear.
Someone may understand the risks and still experience powerful cravings, withdrawal symptoms and repeated cycles of trying to stop and returning to use.
That is one of the defining features of addiction.
For some people, fear of withdrawal becomes one of the biggest barriers to seeking help. Others may have co-occurring anxiety, depression, trauma or other mental health concerns that contribute to continued substance use.
Treatment can address these issues together.
The first step is determining what level of support is appropriate based on the person’s substance use, medical needs, mental health, withdrawal history and recovery environment.
For people in Lexington and Central Kentucky who are struggling with fentanyl or opioid addiction, treatment can provide a structured alternative to the uncertainty of the illicit drug supply.
Lexington Addiction Center provides outpatient addiction treatment in Lexington, Kentucky, including multiple levels of care designed to support people at different stages of recovery.
Depending on clinical needs, treatment may include partial hospitalization programming (PHP), intensive outpatient programming (IOP) and outpatient treatment.
Care can incorporate evidence-based therapies, individual counseling, group support, family involvement, relapse-prevention planning and treatment for co-occurring mental health concerns when appropriate.
Medication-assisted treatment may also be incorporated when clinically appropriate as part of a broader treatment plan for opioid use disorder.
Because Lexington Addiction Center is an outpatient treatment provider, someone experiencing severe intoxication, dangerous withdrawal symptoms or another medical emergency may require medical stabilization or detoxification before outpatient treatment is appropriate.
An assessment can help determine the right starting point.
Getting through withdrawal is only one part of recovering from opioid addiction.
Fentanyl addiction can affect relationships, mental health, employment, routines, decision-making and the ability to manage stress without returning to substance use.
That is why ongoing treatment matters after medical stabilization.
At Lexington Addiction Center, treatment can help clients identify triggers, develop coping strategies, address underlying mental health concerns and strengthen the skills needed to maintain recovery outside of a controlled environment.
Different levels of outpatient care also allow treatment intensity to change as recovery progresses.
Someone may begin with a more structured program and gradually transition toward greater independence as clinical stability improves.
The goal is not simply to stop using one particular batch of fentanyl.
It is to build a recovery plan that reduces the likelihood of returning to an illicit drug supply that continues to become more unpredictable.
Rhino tranq is unlikely to be the last substance to change the illicit opioid market.
The progression from fentanyl to fentanyl mixed with xylazine and now medetomidine demonstrates how quickly the supply can evolve.
For someone using illicit opioids, previous experience offers limited protection.
A familiar-looking substance may contain a different combination or concentration the next time it is purchased.
Treatment offers a way to address the underlying opioid addiction rather than continually trying to anticipate what may appear in the next batch.
If fentanyl or opioid use has become difficult to control, Lexington Addiction Center can help determine whether its outpatient programs are appropriate or whether another level of care should come first.
Rhino tranq is an emerging term for medetomidine, a powerful veterinary sedative increasingly detected in the illicit fentanyl supply. Other reported names include “mede” and “dex.”
Yes. University of Kentucky public health information reports that medetomidine has been identified in the illicit fentanyl supply in several Kentucky counties.
No. Medetomidine and xylazine are different non-opioid sedatives. Both have appeared in fentanyl, but they are different substances and can produce different patterns of intoxication and withdrawal.
“Dex” is one term associated with medetomidine. The nickname may relate to dexmedetomidine, one of medetomidine’s isomers. Street terminology is inconsistent and should not be relied upon to determine what an illicit substance contains.
Naloxone does not directly reverse medetomidine because medetomidine is not an opioid. Naloxone should still be administered during a suspected opioid overdose because fentanyl may also be present.
Naloxone can reverse fentanyl while medetomidine or another non-opioid sedative continues causing significant sedation. Continued unresponsiveness following naloxone requires emergency medical attention.
Reported symptoms include rapid heart rate, severe hypertension, tremors, changes in alertness, chest pain, nausea and vomiting. Severe symptoms may require hospital treatment.
It can be. Severe cardiovascular and autonomic symptoms have been reported, which is why unusual or severe withdrawal symptoms should receive medical evaluation.
Medetomidine replaced xylazine as the most common adulterant in Philadelphia’s illicit opioid supply during the final four months of 2024. That does not mean medetomidine has replaced xylazine throughout Kentucky or nationwide.
Yes. Illicit drug products may contain multiple substances. A person could potentially be exposed to fentanyl, medetomidine, xylazine and other drugs without knowing the complete composition.
Repeated exposure may cause physical dependence. Because medetomidine can be mixed with fentanyl, someone could potentially experience repeated exposure without intentionally seeking medetomidine.
Lexington Addiction Center provides outpatient addiction treatment for people struggling with opioids and other substances. An assessment can help determine whether PHP, IOP or outpatient care is appropriate or whether medical stabilization or another level of care should occur first.
Call 911 for a suspected overdose or serious symptoms such as breathing problems, loss of consciousness, chest pain, seizures, severe changes in heart rate, severe hypertension or major changes in alertness.
The illicit opioid supply is becoming increasingly difficult to predict.
Fentanyl transformed overdose risk. Xylazine introduced another dangerous variable. Medetomidine has now emerged across the country and has been detected here in Kentucky.
For someone living with opioid addiction, the larger problem is not simply whether the next batch contains rhino tranq.
It is that there may be no reliable way to know what the next batch contains at all.
Recovery provides a path away from that uncertainty.
If you or someone you love is struggling with fentanyl, opioid addiction or polysubstance use, contact Lexington Addiction Center to discuss treatment options in Lexington, Kentucky.
Our admissions team can help you understand available programs, verify insurance benefits and determine whether outpatient treatment is an appropriate next step.
If you are experiencing an overdose, severe withdrawal or another medical emergency, call 911.
This article reflects emerging public health information available as of August 2026. Because the illicit drug supply changes rapidly, local medetomidine prevalence and terminology may continue to evolve.
Centers for Disease Control and Prevention. Medetomidine Situation Summary. Updated April 2, 2026.
Centers for Disease Control and Prevention. Medetomidine in the U.S. Illegal Fentanyl Supply Increasing Risk for Overdose and Severe Withdrawal Syndrome. Health Alert Network Health Advisory, April 2, 2026.
Centers for Disease Control and Prevention. Notes from the Field: Suspected Medetomidine Withdrawal Syndrome Among Fentanyl-Exposed Patients — Philadelphia, Pennsylvania, September 2024–January 2025. MMWR, May 1, 2025.
Centers for Disease Control and Prevention. Xylazine: What You Should Know.
University of Kentucky College of Public Health. Know the Risks: Medetomidine.
White House Office of National Drug Control Policy. ONDCP, CDC Release Health Advisory on Medetomidine in Illicit Fentanyl. April 6, 2026.
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