How Long Does Fentanyl Stay in Your System?
Fentanyl 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
Fentanyl is used in hospital settings as an injectable solution, but it may also be prescribed as a an orally dissolving tablet, a spray, a transmucosal lozenge, or in extended-release transdermal patch formulations. But on the street, illicit fentanyl may be encountered as a powder, spiked on blotter paper, combined with or substituted for heroin, or sold as tablets that resemble other opioids.1
Detection times may vary by the specific assay used, but on certain tests, fentanyl may 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) has indicated that fentanyl abuse (non-medical misuse) first appeared in the 1970s.2 Despite its abuse liability, a potent opioid like fentanyl still plays a valuable role in certain treatment settings, as it is used to treat people with severe, chronic painwho have developed tolerance to other opioids.1
Fentanyl may be abused by people who seek its euphoric effects. They may steal it, forge prescriptions, or get it through patients, physicians, and pharmacists. In other cases, it may be inadvertently used as an adulterant of heroin. Much of the current fentanyl abuse and overdose epidemic involves illegally manufactured fentanyl.2
Fentanyl’s potency greatly increases the risk of overdose. It acts on areas of the brain that control breathing, which can lead to pronounced respiratory depression and death. People may not be aware that they are using fentanyl, since illicit forms of the drug are sometimes found mixed with heroin or cocaine.1
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 anywhere from 5 to 14 hours, depending on the specific transmucosal formulation.6
Other factors that may contribute to differences in drug metabolism, which can affect how fast a person processes fentanyl, include:
- Body mass.
- Body fat percentage.
- Hydration status.
- Liver function.
How Can Drug Tests Detect Fentanyl?
- Urine test: Fentanyl is usually not tested on routine drug screenings. Fentanyl-specific toxicology must be specially requested. Studies have shown that fentanyl can show up in urine for up to 24 hours, but is not likely to be detectable beyond 72 hours. Norfentanyl, a metabolite of fentanyl that is produced as the body breaks down the drug, may be detectable for up to 96 hours on some tests.7
- Blood test: One study of post-surgical blood measurements suggests that fentanyl may be detectable 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
- National Institute on Drug Abuse. (2016). DrugFacts: Fentanyl
- Drug Enforcement Administration. (2018). Fentanyl
- 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.
- Medscape. fentanyl (Rx).
- National Library of Medicine, DailyMed. (2011). FENTANYL TRANSDERMAL SYSTEM – fentanyl patch, extended release.
- Twycross, R., Prommer, E., Mihalyo, M., and Wilcock, A. (2012). Fentanyl (transmucosal). Journal of Pain and Symptom Management. 44(1), 131–149.
- 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 saliva. Anesthesia & Analgesia, 76(3), 618-21.
- 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 abuse. American Journal of Forensic Medicine and Pathology, 15(3), 236-41.
- The University of Arizona. (2018). Biological Tests.