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How Long Does Fentanyl Stay in Your System?

fentanyl-stay-in-your-systemFentanyl is a synthetic opioid painkiller that is used to treat severe pain or postsurgical pain. It is between 50 to 100 times more potent than morphine.1

Physicians prescribe it as an injection, transdermal patch, or in lozenges. But on the street, it may be sold as a powder, spiked on blotter paper, combined with or substituted for heroin, or sold as tablets that resemble other opioids.1

Fentanyl can be detected in urine for up to 3 days, in blood for up to 48 hours, and in hair for up to 3 months. Saliva tests are not reliable detectors of fentanyl.

Why Is Fentanyl So Risky?

This opioid drug was first used in the 1960s as an anesthetic under the brand name Sublimaze. The Drug Enforcement Administration (DEA) first reported fentanyl abuse among those without prescriptions in the 1970s.2 However, the medication is still important, as it is used to treat people with severe, chronic painwho have developed tolerance to other opioids.1

Fentanyl is abused by people who seek its euphoric effects and may substitute it for heroin. They may steal it, forge prescriptions, or get it through patients, physicians, and pharmacists. The current fentanyl abuse and overdose epidemic, however, involves illicitly made fentanyl from clandestine labs.2

Fentanyl’s potency greatly increases the risk of overdose. It acts on areas of the brain that control breathing, and it can greatly slow or stop breathing, leading to death. People may not be aware that they are using fentanyl, since it can be mixed with heroin or cocaine.1

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Metabolism Depends on Administration Method

Fentanyl’s half-life can vary depending on how it is administered or abused. A drug’s half-life is the period of time it takes for its concentration in the blood to drop by 50%.3

  • Intravenous fentanyl: The half-life is between 2 and 4 hours, depending on the size of the dose.4
  • Transdermal fentanyl: Often administered via patches, the half-life of the drug when taken in this manner is about 17 hours.5
  • Transmucosal fentanyl: When fentanyl is orally consumed, often in the form of lozenges, it has a half-life of about 5-14 hours, depending on the dose.6

Other factors that can contribute to differences in drug metabolism, which can affect how fast a person processes fentanyl, include:

  • Age.
  • Gender.
  • Body mass.
  • Body fat percentage.
  • Hydration.
  • Liver function.
  • Genetics.

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How Can Drug Tests Detect Fentanyl?

  • Urine test: Fentanyl is usually not tested on routine drug screenings and must be requested. Studies have shown that fentanyl can show up in urine for up to 24 hours, but is not likely to be detectable in 72 hours. Norfentanyl, a metabolite of fentanyl that is produced as the body breaks down the drug, can be detected for up to 96 hours.7
  • Blood test: Studies that have tested fentanyl in the blood after surgery have found that fentanyl can remain in the blood for 5-48 hours depending on the dose (2000 micrograms vs 5000 micrograms). Norfentanyl can remain in the blood for 4 hours.8
  • Hair test: Hair tests can detect fentanyl for up to 3 months.9
  • Saliva test: Even when fentanyl is consumed in lozenge form, it is difficult to detect in the saliva, so this type of drug test is unreliable.7
  1. National Institute on Drug Abuse. (2016). DrugFacts: Fentanyl
  2. Drug Enforcement Administration. (2018). Fentanyl
  3. Ratain, M. and Plunkett, W. (2003). Principles of Pharmacokinetics. In Kufe D.W., Pollock R.E., Weichselbaum R.R., Holland-Frei Cancer Medicine, 6th edition.
  4. Medscape. fentanyl (Rx).
  5. National Library of Medicine, DailyMed. (2011). FENTANYL TRANSDERMAL SYSTEM – fentanyl patch, extended release.
  6. Twycross, R., Prommer, E., Mihalyo, M., and Wilcock, A. (2012). Fentanyl (transmucosal)Journal of Pain and Symptom Management. 44(1), 131–149.
  7. Silverstein J.H., Rieders, M.F., McMullin, M., Schulman, S., Zahl, K. (1993). An analysis of the duration of fentanyl and its metabolites in urine and salivaAnesthesia & Analgesia, 76(3), 618-21.
  8. Schwartz J.G., Garriott J.C., Somerset J.S., Igler E.J., Rodriguez R., Orr M.D. (1994). Measurements of fentanyl and sufentanil in blood and urine after surgical application. Implication in detection of abuseAmerican Journal of Forensic Medicine and Pathology, 15(3), 236-41.
  9. The University of Arizona. (2018). Biological Tests.