“Flysky”: A Street Drug Combining Heroin And Medetomidine

A dangerous new street drug called flysky has been reported in numerous American cities. This lethal substance mixes heroin with medetomidine, a sedative used in veterinary medicine. At least two people have died from flysky in Pennsylvania, and the drug has also appeared in Chicago and Philadelphia.

What makes flysky deadly is that it doesn’t respond to Narcan, the medicine that usually saves people from drug overdoses. When someone overdoses on standard heroin, Narcan can bring them back to life. Due to flysky containing medetomidine, which Narcan cannot reverse, many people still die during overdose even when they get help.

The drug is spreading fast because dealers are integrating it into the regular drug supply. Many people think they’re buying and ingesting heroin but they’re actually taking flysky. This heightens the chance of overdose and death because people can’t prepare for the different effects or know that Narcan won’t help them.

Why People Use Flysky

Some people use flysky because drug dealers tell them it’s stronger or lasts longer than regular heroin, giving the impression that they’re getting a better deal for their money.

Others think they’re buying regular heroin or fentanyl but get flysky instead because dealers mix it into the drug supply, unbeknownst to the buyer. People who are addicted to opioids may also try flysky because it’s sometimes cheaper or easier to find.

Most people don’t understand how much more dangerous flysky is compared to other street drugs. They may have even survived overdoses in the past with help from Narcan, so they think they can handle this new drug. Unfortunately, this naive confidence can be deadly because flysky works differently and doesn’t respond to the usual life-saving treatments.

Fayette County District Attorney Michael Aubele warns, “If you overdose on medetomidine, Narcan is not going to save you.”

How Flysky Is Used

People use flysky by injecting it into their veins, snorting it through their nose, or smoking it. Drug dealers sell it in small bags on the street, sometimes with labels that say “flysky” but often without any warning about what’s inside.

The drug looks like a white, brown, or tan powder, so consumers can’t tell the difference between it and regular heroin based on appearance. Some dealers may use code names or symbols on the bags to identify different batches.

The medetomidine found in flysky is either diverted from veterinary supplies or illicitly manufactured without quality controls. Unlike pharmaceutical-grade veterinary medetomidine, street versions have no standardized dosing or purity, so the strength varies dramatically from bag to bag. Drug dealers don’t measure accurately or follow safety protocols when they mix these drugs together, so each batch can be different in strength and effects.

Additionally, many people who buy flysky don’t know what they’re getting because of untruthful marketing. Dealers are marketing flysky as a new, stronger alternative to fentanyl, but they don’t explain the serious risks or mention that Narcan won’t work.

The Dangers Of Abusing Flysky

The biggest danger with flysky is that Narcan cannot save someone who overdoses on it. Fayette County District Attorney Michael Aubele warns, “If you overdose on medetomidine, Narcan is not going to save you.” This is because medetomidine works on different parts of the brain than heroin does. While Narcan can block heroin’s effects on opioid receptors, it has no power over medetomidine’s effects.

Fentanyl test strips may be able to detect fentanyl in a substance, but they can’t detect medetomidine. A negative fentanyl test does not mean a substance is safe. At this time, there is no widely available street-level test that can identify medetomidine before use. This is another reason why flysky is particularly dangerous.

Medetomidine is 200 to 300 times more powerful than xylazine, another animal tranquilizer that has been introduced into the illegal drug supply. Even tiny amounts can cause life-threatening effects including heart problems, breathing difficulties, and loss of consciousness.

Since street dealers don’t measure doses carefully and have no medical training, users never know how much medetomidine they’re taking, making every use potentially fatal. The drug is so potent that what may seem like a normal amount could actually be a deadly overdose.

The combination creates unpredictable and dangerous effects in the body that confuse both users and medical professionals. While heroin typically slows down breathing and heart rate in predictable ways, medetomidine can cause opposite effects like severe agitation and irregular heartbeats at the same time.

This confusion makes it very hard for doctors and paramedics to treat overdoses because the symptoms don’t follow normal patterns. In May 2024, Chicago saw 181 overdoses in just one week, with 12 involving medetomidine.

Signs And Symptoms Of Flysky Overdose

A flysky overdose looks different from a regular heroin overdose and is far more serious, requiring immediate emergency care. The most common sign is a slow heart rate, also known as bradycardia, that can be deadly if not treated quickly.

People overdosing on flysky usually swing between being heavily sedated and very agitated and confused, which will be disturbing for bystanders to witness. Unlike regular opioid overdoses that cause sleepiness and slow breathing, flysky can cause opposite symptoms at the same time, making it difficult to pinpoint what is happening.

Heart and blood pressure problems are serious with flysky overdoses and can continue for hours or days. People may have deadly, unpredictable changes in blood pressure, irregular heartbeats, and heart rates that go from very fast to very slow without warning. Their breathing may become slow and shallow or stop completely, but the breathing problems don’t improve with interventions like Narcan or oxygen.

Some people experience what doctors call “autonomic storms”, or periods where their body’s automatic functions such as breathing, body temperature, blood pressure, and heart rate fluctuate erratically.

The most important warning sign of overdose is that the person doesn’t get better after receiving Narcan. In normal overdoses, Narcan wakes people up within minutes and helps them breathe immediately. With flysky, people stay unconscious even after getting multiple doses of Narcan.

Most people who overdose on flysky need intensive care, and many require machines to help them breathe and medications to support their heart and blood pressure. Between October 2024 to March 2025, Pittsburgh, Pennsylvania, hospitals found that nine out of 10 people with medetomidine exposure needed intensive care in order to survive.

What To Do During A Flysky Overdose

If someone is overdosing on flysky, 911 should be called immediately. Even though it may not work, administer Narcan if available, as it will help if opioids are involved in the overdose.

To that point, most flysky overdoses typically contain fentanyl or other opioids, and Narcan will address those components even if it cannot reverse medetomidine. Withholding Narcan because of flysky concerns could cost a life.

Stay with the person and try to keep them awake and breathing, and prepare to give chest compressions or mouth-to-mouth if they stop breathing. When the paramedics arrive, tell them what drugs the person took, and include the street name or what the bag looked like. The faster someone gets to a hospital, the better their chances of surviving a flysky overdose.

Treatment Options For Substance Abuse

There are a range of treatment services available at drug rehab centers for people who want to stop using flysky or other substances.

Common addiction recovery services include:

• residential treatment programs
• outpatient programs
• family therapy
• support groups such as Narcotics Anonymous (NA) or SMART Recovery
• medications for opioid use disorder (MOUD) including methadone, buprenorphine (Suboxone), and naltrexone (Vivitrol)
• individual therapy
• group therapy
• dual diagnosis treatment for people with co-occurring mental health issues
• relapse prevention
• case management
• aftercare support

With a combination of medical care, therapy, and peer support, people can free themselves from addiction and start to rebuild their lives.

For people who are currently using opioids and not ready or able to stop, reducing risk is still possible. Never use alone, because having someone present who can call 911 and administer Narcan dramatically increases your odds of survival.

Carry naloxone and make sure people around you know how to use it. Avoid using a full dose of any substance when trying a new supply, as potency varies significantly. Local syringe service programs and harm reduction organizations can provide naloxone, fentanyl test strips, and connection to treatment when you are ready.

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Written by the Addiction Resource Editorial Staff