How Long Does Carfentanil Stay in Your System?

Related to fentanyl, carfentanil is an extremely powerful opioid drug that is 10,000 times stronger than morphine. Used as an animal anaesthetic, carfentanil can stay in the system for days and can easily kill humans who consume it unless they receive assistance and treatment.

As dangerous as some drugs are, there are often substances that can be worse, much worse.

Carfentanil is one of those drugs. It’s a synthetic (man-made) opioid drug that is used as anaesthesia for animals . It’s 10,000 times stronger than another opioid, morphine, and 100 times stronger than fentanyl, which is a related drug that’s also an extremely powerful opioid. The dangers of it can be found in the opioid abuse statistics.

Because of this potency, people might wonder, How long does carfentanil last? They’re curious about the power it can have and the damage it can do.

How long does carfentanil stay in your system?

Understanding carfentanil’s half-life could be a good way to determine how long this drug or other substances remain in the body. A half-life is the amount of time it takes for a drug to reduce to one half its peak concentration.

According to carfentanil drug tests:

  • Carfentanil’s half-life is about 7.7 hours.
  • Naltrexone, a drug used to block the effects of carfentanil and other opioids, has a half-life that lasts around 3.7 hours.

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This means that the carfentanil half-life is almost double the half-life of drugs that are used to treat its effects. Carfentanil remains in the body in a higher concentration for a longer amount of time than other, less harmful drugs.

It’s not surprising, then, that the state of Ohio reported almost 400 carfentanil-related deaths in just July through December of 2016.

How long does carfentanil stay in your urine?

Another problem with carfentanil is that it can be difficult to spot. Determining a carfentanil drug test detection time can be challenging because many standard drug tests aren’t able to find the presence of carfentanil.

When does carfentanil show up in a drug test? When people have the correct screenings for it. If people do have such screenings, they could address the question, How long is carfentanil detectable in urine?

Such urine tests can detect the presence of carfentanil, fentanyl, and similar substances for 24 to 72 hours after people last use them.

That means that carfentanil and fentanyl, powerful drugs, can linger in the body days after people consume them. They can easily hurt or kill people unless they find prompt assistance and treatment.


  • – Carfentanil: A Dangerous New Factor in the U.S. Opioid Crisis
  • pubmed.ncbi.nlm.nih.govPharmacokinetics and Pharmacodynamics of Carfentanil and Naltrexone in Female Common Eland (Taurotragus oryx)
  • – Notes from the Field: Overdose Deaths with Carfentanil and Other Fentanyl Analogs Detected — 10 States, July 2016–June 2017
  • pubmed.ncbi.nlm.nih.govAn Analysis of the Duration of Fentanyl and Its Metabolites in Urine and Saliva

Medical disclaimer:

Sunshine Behavioral Health strives to help people who are facing substance abuse, addiction, mental health disorders, or a combination of these conditions. It does this by providing compassionate care and evidence-based content that addresses health, treatment, and recovery.

Licensed medical professionals review material we publish on our site. The material is not a substitute for qualified medical diagnoses, treatment, or advice. It should not be used to replace the suggestions of your personal physician or other health care professionals.

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