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How Long Does Fentanyl Stay in Urine? Everything To Know About Fentanyl Drug Testing

How Long Does Fentanyl Stay in Urine

Key Points

  • Fentanyl can stay in your body for up to 2 weeks.
  • This potent opioid is at the center of the opioid crisis in the US and was primarily responsible for over 70,601 deaths in 2021.
  • How long fentanyl stays in your body depends on age, weight, gender, family genetics, frequency of doses, and strength of the last dose.
  • The difference between a dose that won’t kill you and one that will is very small and sometimes unpredictable.

Fentanyl and its metabolite norfentanyl can be detected for up to 13 days in urine samples following the last dose.[1]

This is considerably longer than the 2-4 day window for most other opioids, possibly because fentanyl is much stronger than other opioids.

However, research suggests that small, legal doses of fentanyl given in clinical settings will likely clear your system within 3 days.[2]

What is Fentanyl?

Fentanyl is a synthetic opioid agonist that is approved to treat breakthrough, post-operative, or chronic cancer-related pain for which non-opioid alternatives are insufficient.

It’s incredibly strong – 50 times more potent than heroin and 100 times more potent than morphine.[3] As such, the difference between the therapeutic and fatal doses is minimal.

Fentanyl is the heart and soul of the opioid drug crisis in the United States. Many people unknowingly use drugs that have been cut with fentanyl and overdose.

Fentanyl’s Mechanism of Action

Fentanyl attaches to opioid receptors in the central nervous system.[4] These receptors are responsible for the subjective experience of pain getting transmitted throughout the body. When fentanyl binds to them, it signals the brain to release dopamine from the hypothalamus.

Dopamine is a feel-good chemical that your brain releases when you are engaging in healthy activities such as running, exercising, eating, drinking, listening to good music, and having sex. It trains us to want to repeat the activity.

Fentanyl elicits a stronger dopamine release than natural opioids your body can produce. This is also what makes it addictive.

What is Opioid-Use Disorder?

Opioid-use disorder (OUD) is a medical condition characterized by the problematic use of opioids leading to clinically significant impairment or distress. OUD affects over 2.1 million people in the United States and over 16 million worldwide.[5] It causes 120,000 deaths worldwide. While there are reversal treatments for opioid overdoses, such as Narcan, opioid overdoses are still deadly.

To make a formal diagnosis, a licensed physician must use the 11 criteria contained in the DSM-V. Two (2) out of the eleven (11) criteria must be present within 12 months for the clinical definition of opioid-use disorder to be met:

  • Continued use despite degrading mental and physical health
  • Continued use created difficulties within personal relationships
  • Less time spent on hobbies
  • Negative consequences for work-related responsibilities
  • Using more and more time to locate, use, and recover from drugs
  • Increasing quantity of drugs being used
  • Cravings
  • Can’t stop even if the attempt is made
  • More and more drugs are needed to achieve the same effect
  • Continued use despite physically dangerous settings
  • Painful sensations if the attempt is made to stop taking the drug

If you think you meet any of these criteria, schedule an appointment with an addiction specialist as quickly as possible.

Fentanyl Use Statistics

Fentanyl is used both legally and illegally.

Legal Uses for Fentanyl

First approved for use in the US in 1968, the US government now advises physicians to only use fentanyl for patients with persistent cancer-related pain that a non-opioid alternative cannot treat.[6]

In 2021, there were 2.4 million legal prescriptions for brands of medications containing fentanyl.[7] This represents an almost ⅔ reduction in the sheer volume of prescriptions since 2015, possibly due to the growing public awareness of the opioid crisis.

It can be administered intravenously, intramuscularly, transdermally, intranasally, and intrathecally.

Illegal Use

It’s easier for dealers to smuggle a small bag of fentanyl into the US than a kilo-sized brick of another drug. Combined with its relatively cheap manufacturing cost, it often gets cut into packages of more expensive drugs.

This makes “cut” drugs cheaper to sell and more deadly to use.

In 2021, there were 70,601 overdose deaths attributed primarily to fentanyl in the US.[8] Even though fentanyl overdoses are responsive to naloxone reversals, they must be administered as quickly as possible.

Worse yet, the veterinary sedative called “xylazine” has been found mixed with seized fentanyl in 48 out of 50 states.[9] Since it isn’t an opioid, it isn’t responsive to naloxone reversals.

Windows of Detection for Fentanyl in Urine and Your Body

Fentanyl is absorbed through your liver and eliminated via your kidneys. There are a variety of factors that determine how long it will stay in your system, from blood and urine to hair and saliva.[10][11][12]

Blood Urine Hair Saliva
Up to 72 hours 1-3 days for those without OUD

Up to 28 days for those with OUD

Up to 90 days 12 hours

Factors That Influence The Fentanyl Elimination Timeline

Your age, weight, gender, family genetics, frequency of dosing, and potency of last dose all influence fentanyl’s elimination time.

The elimination half-life of a given substance is the time it takes for 50% of a substance to be eliminated from your body. It takes 4-5 elimination half-lives to eliminate a substance from your body statistically.

The half-life of fentanyl is anywhere from 3-7 hours, which means it should be statistically eliminated from your body between 12-15 to 28-35 hours from the time of the last dose.[13] However, research has shown that fentanyl can be detected in urine up to 13.3 days after the last dose.[14]

Common Side Effects of Fentanyl

Side Effects of Fentanyl
One common side effect of therapeutic levels of fentanyl is narcotic ileus (aka constipation). Other mild effects of fentanyl include euphoria, confusion, visual disturbances, and drowsiness.[15]

These symptoms are usually classified as non-threatening and do not persist once the drug has left the system.

Dangerous Side Effects of Fentanyl

Many fatalities are associated with fentanyl because the difference between therapeutic and fatal doses is so small.

There are many dangerous side effects of fentanyl:[16]

  • Respiratory depression
  • Nausea
  • Erratic appendage movements
  • Hallucinations
  • Degraded cognition and reduced ability to focus
  • Muscle rigidity
  • Chemical Dependency
  • Loss of consciousness
  • Low blood pressure
  • Coma
  • Death

Treatment for Fentanyl Addiction

If you or someone you love is addicted to fentanyl, seek treatment immediately. A drug as potent as fentanyl requires a comprehensive treatment plan, including multiple treatment modalities, for you to recover successfully. Self-will alone will likely not be enough.

Ocean Recovery can help you by creating a custom treatment plan. We are a premier addiction treatment center in Southern California, that offers luxury rehab facilities and compassionate care.

Let’s make your transition to recovery comfortable and successful. Our team of specialists is ready to join you on your journey to recovery with compassion, skill, insight, and years of experience.

You might think you have it under control, but fentanyl is a dangerous drug.

There is a small difference between a dose that won’t kill you and one that will. Don’t take that chance anymore. If you’ve tried to stop abusing fentanyl, but you can’t, let us tell you there is still hope.

It might seem unlikely, but there can be a future in which you are free of chemical dependency. If that sounds good to you, start seeking a credentialed addiction treatment facility that can cater to your needs, history, and ideal lifestyle.

Frequently Asked Questions About Fentanyl

Fentanyl produces analgesia that mitigates against breakthrough, post-operative, or persistent cancer-related pain. While it doesn’t take it away completely, the subjective experience of pain will be greatly reduced.

However, the difference between the therapeutic and fatal dose is very small. So, fentanyl can just as easily produce dangerous effects such as respiratory depression, chemical dependency, loss of consciousness, coma, and death.

If your breathing rate drops too low, oxygenated blood will not reach the brain, at which point brain death occurs after several minutes.

The symptoms of fentanyl overdose include unconsciousness, pinpoint pupils, gurgling sounds, blue lips, shallow breathing, limp body, skin discoloration, and clammy skin.[17]

The first thing to do if you suspect someone has overdosed on opioids is to administer a dose of Narcan if it is available. Narcan is an opioid antagonist, which means it can reverse the effects of other opioids.

The next thing to do, even if you don’t have Narcan, is call 911. Tell the dispatcher where you are and wait until they can come to you.

While you remain with the person, ensure their breathing airway is unobstructed and that they are positioned so that they are not a danger to themselves or others.

The maximum time fentanyl stays in urine depends on whether you have an opioid use disorder or not. If you don’t have an opioid use disorder, it should clear your system in 3 days. If you have an opioid use disorder, it could take up to 13 days to clear it.

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The internet contains a vast amount of misinformation, but when it comes to your health only peer reviewed, research centered data matters. At Ocean Recovery, all content published throughout our website has been rigorously medically reviewed by a doctorate level clinician, and cross checked for medical accuracy. Our editorial process helps our readers trust that the information they are consuming is factual and based upon scientific data. Your health is our top priority, find out more about how we safeguard the integrity of information on our website. Read More About Our Process

[1][14] Huhn, A. S., Hobelmann, J. G., Oyler, G. A., & Strain, E. C. (2020, September 1). Protracted renal clearance of fentanyl in persons with opioid use disorder. Drug and alcohol dependence.

[2][10][12] Silverstein, J. H., Rieders, M. F., McMullin, M., Schulman, S., & Zahl, K. (n.d.). An analysis of the duration of fentanyl and its metabolites in urine and saliva. Anesthesia and analgesia.

[3][17] Centers for Disease Control and Prevention. (2023, September 6). Fentanyl facts. Centers for Disease Control and Prevention.

[4][13] Ramos-Matos, C. F., Bistas, K. G., & Lopez-Ojeda, W. (n.d.). Fentanyl – StatPearls – NCBI Bookshelf -.

[5] Dydyk, A. M., Jain, N. K., & Gupta, M. (n.d.). Opioid use disorder – statpearls – NCBI bookshelf .

[6] U.S. National Library of Medicine. (n.d.). Fentanyl: Medlineplus drug information. MedlinePlus.

[7] Fentanyl (trade names: Actiq®, FENTORATM, Duragesic®). (n.d.).

[8] U.S. Department of Health and Human Services. (2023, September 25). Drug overdose death rates. National Institutes of Health.

[9]United States Drug Enforcement Administration. DEA Reports Widespread Threat of Fentanyl Mixed with Xylazine | (n.d.).

[11] Maximum detection time of substances in urine. (n.d.). 

[15][16]U.S. Department of Health and Human Services. (2023, March 3). Fentanyl drugfacts. National Institutes of Health. 

Last medically reviewed February 5, 2024.