What Is Medetomidine? The New Drug Hiding in the Fentanyl Supply

Something has changed in the illicit drug supply, and most people using street opioids don’t know about it yet.

For the past several years, xylazine, known on the street as “tranq”, made headlines as a dangerous additive being mixed into fentanyl. Now, a newer and more potent veterinary sedative called medetomidine is quietly taking its place. Street names include Dex, Rhino Tranq, and Mede.

Unlike fentanyl, medetomidine is not an opioid. That distinction matters enormously, because Narcan won’t reverse it.

At Brooks Healing Center, we believe that understanding what is in the drug supply is the first step toward protecting yourself and the people you love.

What Is Medetomidine?

Medetomidine is a powerful veterinary sedative used by veterinarians to sedate animals during medical procedures. It is not approved for human use in the United States.

It belongs to a class of drugs called alpha-2 adrenergic agonists, the same class as xylazine and clonidine. These drugs work by slowing activity in the central nervous system, lowering heart rate, reducing blood pressure, and causing deep sedation.

A closely related medication, dexmedetomidine (brand name Precedex®), is used in hospital ICUs to sedate critically ill patients under close medical supervision. The street drug medetomidine is its veterinary cousin — unregulated, unmonitored, and increasingly showing up in street fentanyl without users’ knowledge.

Why Is Medetomidine Being Added to Fentanyl?

Drug suppliers add medetomidine to fentanyl for the same reason they added xylazine — it deepens and extends the sedative effect, making the product feel more potent. It is cheap, widely available through veterinary supply channels, and not yet scheduled as a controlled substance in most states.

When law enforcement and regulators cracked down on xylazine, medetomidine emerged to fill the gap. In Philadelphia, the shift happened rapidly:

• May 2024: Medetomidine was found in 29% of fentanyl samples tested
• November 2024: That figure had risen to 87%, while xylazine dropped from nearly 100% to 42%

As of 2025, medetomidine has been identified in drug supplies across at least 18 states and Washington D.C., including major cities in Pennsylvania, Illinois, California, Ohio, and spreading into the Southeast.

Medetomidine vs. Xylazine: What’s Different?

This is one of the most common questions in harm reduction communities right now. People familiar with tranq dope want to know: is this the same thing? Is it worse?

The short answer is: it is related, but significantly more dangerous.

Feature	Xylazine (“Tranq”)	Medetomidine (“Dex”)
Drug class	Alpha-2 agonist	Alpha-2 agonist
Approved for human use	No	No
Potency vs. xylazine	Baseline	100–200x more potent
Reversed by naloxone	No	No
Causes skin wounds	Yes — severe necrosis reported	Not currently associated with wounds
Withdrawal severity	Moderate — anxiety, restlessness	Severe — ICU admission often required
Withdrawal onset	Gradual	Can begin within 2 hours of last use
Vital sign changes in withdrawal	Rare	Common — dangerous spikes in heart rate and blood pressure

The absence of wounds is the one area where medetomidine is less damaging than xylazine. In harm reduction forums, some have noted this as a grim improvement. But the withdrawal picture is significantly worse, and the potency increase means the margin for error is much smaller.

Medetomidine vs. Dexmedetomidine: What’s the Difference?

This comes up frequently because the names are similar and the drugs are chemically related. Here is the key distinction:

	Medetomidine	Dexmedetomidine (Precedex®)
What it is	Veterinary sedative	Hospital ICU sedative
Approved for humans	No	Yes — by prescription only
How it’s used medically	Sedation in dogs and cats	Sedation for critically ill patients on ventilators
How it appears in the drug supply	Mixed into street fentanyl without users’ knowledge	Not found in street supply — it is a controlled hospital medication
Available without prescription	No — but bulk powder is trafficked illicitly	No
Street name	Dex, Rhino Tranq, Mede	N/A

Medetomidine is a racemic mixture, meaning it contains two mirror-image molecules, one of which is dexmedetomidine. When people on the street refer to “Dex,” they are referring to medetomidine, not the hospital medication. The confusion between the two names is one reason clinicians sometimes miss the diagnosis, a patient testing positive for dexmedetomidine metabolites may initially appear to have received a hospital medication rather than an illicit adulterant.

What Does a Medetomidine Overdose Look Like?

Because medetomidine is almost always mixed with fentanyl, an overdose typically looks like an opioid overdose, but with key differences that complicate response:

• Slow or stopped breathing
• Pinpoint pupils
• Profound sedation that does not respond to naloxone
• Severely slowed heart rate (bradycardia), pulse rates as low as 32–50 beats per minute have been documented
• Low blood pressure

The critical warning sign is a person who remains unresponsive or deeply sedated even after multiple doses of Narcan. This is not a sign that the naloxone isn’t working on the opioid, it means medetomidine is keeping the person sedated separately.

Naloxone should still be administered in any suspected overdose involving street fentanyl, because it will address the opioid component. But rescue breathing and emergency medical care are essential — naloxone alone is not enough.

Medetomidine Withdrawal: Why It Requires Medical Attention

This is where medetomidine separates itself from almost every other adulterant in the current drug supply.

People who have been unknowingly using fentanyl containing medetomidine can develop physical dependence on it, without ever intending to use it. When they stop, or when they enter treatment and begin withdrawal, the results can be severe and life-threatening.

Withdrawal symptoms can begin within 2 hours of last use and include:

• Severe nausea and vomiting that does not respond to standard medications
• Uncontrolled tremors
• Profuse sweating
• Dangerously elevated heart rate (tachycardia)
• Dangerous spikes in blood pressure that can damage the heart and brain
• Agitation and confusion
• Altered mental status

In Philadelphia, where medetomidine hit first, 91% of hospitalized withdrawal patients required ICU-level care. Standard opioid withdrawal protocols, medications that worked reliably for fentanyl and xylazine withdrawal — frequently failed to control symptoms.

The CDC has documented this withdrawal syndrome in two separate reports, describing it as life-threatening and requiring substantial escalation in care compared to typical opioid withdrawal.

What is happening physiologically is essentially the opposite of the drug’s sedative effect. When the alpha-2 receptors that medetomidine had been suppressing are suddenly without it, the sympathetic nervous system rebounds, heart rate and blood pressure spike to dangerous levels in what clinicians describe as a profound autonomic crisis.

This is not withdrawal that can safely be managed at home.

Can You Test for Medetomidine?

This is one of the most frequent questions in harm reduction communities, and the answer is evolving.

Standard fentanyl test strips do not detect medetomidine. Standard hospital toxicology panels often miss it as well — in several documented cases, medetomidine was only confirmed through retrospective specialized testing after patients had already been discharged.

Medetomidine-specific test strips are now commercially available through harm reduction organizations. They work similarly to fentanyl test strips, a small amount of drug residue is dissolved in water and the strip is dipped. One line means positive (medetomidine detected), two lines means negative.

Availability varies by region. Philadelphia-based harm reduction organizations are distributing them, and some areas of the country are beginning to stock them. If you are in contact with someone who uses street opioids, checking with local harm reduction services about strip availability is worthwhile.

Medetomidine and the Current Drug Supply: A Snapshot

Location	Finding
Philadelphia, PA	87% of fentanyl samples contained medetomidine by Nov 2024
Pittsburgh, PA	ICU cases documented Oct 2024–March 2025
Chicago, IL	170+ suspected cases in a single week cluster
New York State	Public health alert issued December 2025
18+ U.S. states	Confirmed presence in drug supply as of 2025
Southeast U.S.	Increasing detection; Tennessee and surrounding states on alert

A Section for Families: What You Need to Know

If someone you love uses street opioids, or you suspect they might, this section is for you.

You may not know it’s happening. Medetomidine is not something people seek out. It is being added to fentanyl without buyers’ knowledge. Your loved one may have no idea their supply has changed.

Narcan may not be enough. If you witness an overdose and administer naloxone, the person may still remain unconscious. This does not mean you did something wrong. It means the drug supply has changed. Give all doses of naloxone you have, begin rescue breathing if you know how, and call 911 immediately. Do not leave them alone.

Withdrawal is a medical emergency. If your loved one decides to stop using, or enters treatment and begins to withdraw, watch for signs that go beyond typical opioid withdrawal, extreme agitation, uncontrollable vomiting, shaking, complaints of racing heart, or confusion. These are warning signs that medetomidine withdrawal is occurring and that hospital-level care is needed. Do not attempt to manage this at home.

Getting into treatment is more urgent, not less. Some families wonder whether to wait for their loved one to “be ready.” With medetomidine in the supply, the window for a safe detox at home is essentially closed. Medically supervised detox is not just recommended, it is the only safe option for someone who may be dependent on both fentanyl and medetomidine simultaneously.

Medetomidine in Tennessee: What State Officials Are Saying

Medetomidine is not a distant problem. It is here.

In September 2025, the Tennessee Bureau of Investigation (TBI), together with the Tennessee Department of Mental Health and Substance Abuse Services and the Tennessee Department of Health, issued a joint public safety alert confirming that medetomidine had been detected in Tennessee crime labs.

The TBI described it plainly: “Medetomidine is a veterinary anesthetic with powerful sedative properties, far more potent than Xylazine, and it can cause prolonged sedation. It has appeared in our crime labs and, alarmingly, it is often mixed with fentanyl.”

State officials issued the alert after observing overdose spikes linked to medetomidine in other states, warning Tennessee communities that the same pattern was beginning to emerge locally.

What Tennessee officials are recommending:

• Keep naloxone on hand — free naloxone and training are available through Tennessee’s Regional Overdose Prevention Specialists at TN.gov/behavioral-health/rops
• Call or text the Tennessee REDLINE at 1-800-889-9789 for free, confidential treatment referrals available 24 hours a day, 7 days a week
• Spread awareness — the TBI specifically asked the public to share the alert to help protect communities

What this means for Middle Tennessee and surrounding areas:

Tennessee sits along major drug trafficking corridors connecting the Southeast to the Midwest. Medetomidine followed xylazine’s geographic spread — beginning in the Northeast and Mid-Atlantic, moving through Ohio and into the South. Given that medetomidine was already confirmed in Tennessee crime labs in September 2025, and detection rates nationally have continued climbing into 2026, the presence of this adulterant in the Middle Tennessee drug supply should be treated as confirmed, not theoretical.

Anyone in the Nashville, Murfreesboro, Chattanooga, or surrounding areas who uses street opioids, or who has a loved one who does — should assume that medetomidine may be present in the supply.

Brooks Healing Center is located in Middle Tennessee outside of Nashville, and serves patients from across the state and region. Our medical detox program provides around-the-clock nursing and provider support specifically because the drug supply has changed. Withdrawal from fentanyl that contains medetomidine requires a level of medical oversight that cannot be safely provided at home or in an unsupervised setting, which our medication-assisted treatment program can provide.

If you or someone you love is using street opioids in Tennessee, the risk is real and it is current. Help is close.

Frequently Asked Questions

Sources

2. CDC MMWR. (2025, May). Notes from the Field: Suspected Medetomidine Withdrawal Syndrome Among Fentanyl-Exposed Patients — Philadelphia, Pennsylvania, September 2024–January 2025. https://www.cdc.gov/mmwr/volumes/74/wr/mm7415a2.htm
3. CDC MMWR. (2025, May). Notes from the Field: Severe Medetomidine Withdrawal Syndrome in Patients Using Illegally Manufactured Opioids — Pittsburgh, Pennsylvania, October 2024–March 2025. https://www.cdc.gov/mmwr/volumes/74/wr/mm7415a3.htm
4. New York State Department of Health. (2025, December 19). Public Health Alert: Medetomidine detected in drug supply. https://www.health.ny.gov/press/releases/2025/2025-12-19_synthetic_sedative.htm
5. Philadelphia Department of Public Health. (2025). Medetomidine: What you need to know. https://www.substanceusephilly.com/medetomidine
6. STAT News. (2025, May 1). Sedative ‘dex’ is replacing ‘tranq’ in illegal drug supply and causing excruciating withdrawal. https://www.statnews.com/2025/05/01/medetomidine-replacing-xylazine-in-fentanyl-increases-overdose-danger-withdrawal-risks/
7. Pharmacy Times. (2025). Medetomidine: The Demon in the Illicit Fentanyl Supply. https://www.pharmacytimes.com/view/medetomidine-the-demon-in-the-illicit-fentanyl-supply
8. ASAM Practice Pearls. (2026, February). Understanding Medetomidine: Emerging Challenges for Addiction Medicine. https://asampracticepearls.podbean.com/e/understanding-medetomidine-emerging-challenges-for-addiction-medicine
9. Partnership to End Addiction. (2025). Medetomidine in Fentanyl: A New Risk for Opioid Users. https://drugfree.org/article/medetomidine-in-fentanyl-a-new-risk-for-opioid-users/
10. Psychoactives Journal. (2025, October). Profound Opioid and Medetomidine Withdrawal: A Case Series and Narrative Review. https://www.mdpi.com/2813-1851/4/4/37
11. Emergency Medicine News. (2025, August). Street Drug Update: Five Key Questions About Medetomidine. https://journals.lww.com/em-news/fulltext/2025/08000/street_drug_update__five_key_questions_about.6.aspx
12. Tennessee Bureau of Investigation, Tennessee Department of Mental Health and Substance Abuse Services, & Tennessee Department of Health. (2025, September 23). Public Safety Alert: Medetomidine detected in Tennessee illicit drug supply. https://www.wsmv.com/2025/09/23/tbi-warns-public-spike-overdoses-veterinary-anesthetic-with-sedative-properties/