When taken intravenously, fentanyl has an elimination half-life of approximately 2 to 4 hours in adults, meaning it takes approximately 11 to 22 hours to completely leave your system.

Although many people had never heard of fentanyl before it claimed the life of the musician Prince in April 2016, this synthetic opiate pain reliever is one of the strongest opiates available today. It’s 50 to 100 times more potent than morphine. As a result, it’s often used to relieve severe pain, especially after surgery, during cancer treatment, and to manage breakthrough pain.

In its prescription form, fentanyl is known by names such as Actiq, Duragesic, and Sublimaze. However, many people obtain fentanyl without a prescription on the black market. When used for recreational purposes, fentanyl typically comes in the form of powder, spiked on blotter paper or mixed with heroin, cocaine or other street drugs to amplify the potency.

How Long Does Fentanyl Stay in Your System?

Fentanyl abuse is dangerous and even deadly. In March 2015, the Drug Enforcement Agency (DEA) issued a nationwide alert identifying fentanyl as a threat to public health and public safety, and data by the CDC show that Fentanyl helped drive record-high overdose deaths in 2020.

Fentanyl Half-Life & How Long It Takes to Leave Your System

It is important to understand fentanyl’s half-life to determine how long it will stay in your system. Elimination half-life refers to how long it takes for half of a single dose of a drug to leave the body.

The elimination half-life of fentanyl is subject to some variation based on the method by which it’s administered. When taken intravenously, fentanyl has an elimination half-life of approximately 2 to 4 hours in adults, meaning it takes approximately 11 to 22 hours to leave your system.

If you use the patch or lozenge, fentanyl exhibits a half-life of approximately 7 to 17 hours, and it will take around 36 hours for the drug to completely leave your system after you stop using.

As fentanyl breaks down in your system, it leaves behind traces called metabolites. These metabolites stay in your system longer, meaning that a thorough drug test could detect fentanyl in your system even several days after you stop taking it.

Related Topics:
How long do opioids stay in your system
How long does suboxone stay in your system

Will Fentanyl Show Up on a Drug Test?

Although fentanyl is much stronger than other opiates, it’s not commonly tested for on standard drug tests, which often aim to detect the presence of opioids that metabolize into morphine. Since fentanyl doesn’t metabolize into morphine, it’s unlikely to be detected unless an advanced drug test is ordered.

However, if an advanced drug test is ordered, fentanyl is easily detected through urine, hair, saliva, and blood tests. Fentanyl can be detected in:

  • Urine – for eight to 24 hours
  • Blood – for up to 12 hours
  • Saliva – for one to three days
  • Hair – for up to 90 days

How Long Does Fentanyl Stay in Your Urine?

While often undetected by standard drug tests, an advanced urine drug test can be used to identify fentanyl. In this case, fentanyl can be recognized in urine for eight to 24 hours, depending on various factors including age, weight and more. While urine tests may not recognize fentanyl after a full day, other methods still detect it and the drug can continue to wreak havoc on the body after improper use.

How Long Does Fentanyl Stay in Your Hair?

Hair is one of the most telling features of a person’s health. Because of its relatively slow growth process, it is often one of the most accurate health history timelines. For this reason, hair drug testing can be one of the most effective and telling signs of long-term drug use. Fentanyl can be detected in hair for up to 90 days, about three months.

How Long Does Fentanyl Stay in Your Blood?

Blood testing is one of the least effective methods of detecting drug use over a long period. Fentanyl can only be recognized in the bloodstream for up to 12 hours. Although it typically isn’t detectable in the blood for longer than half a day, the negative side effects of long-term opioid use manifest themselves in various ways, including life-threatening addiction and potential overdose.

How Long Does Fentanyl Stay in Your Saliva?

Saliva can be used for a variety of tests — from DNA to drug testing. Doctors may take a saliva swab or spittle sample to learn more about a patient. Saliva drug tests are often more accurate than urine or blood tests as they can detect fentanyl for one to four days after use.

What Influences How Long Fentanyl Stays in Your System?

There are a variety of factors that influence how long fentanyl stays in your system after your last dose. Some of these variables include:

  • Age
  • Weight
  • Height
  • Body mass
  • Body fat
  • Genetics
  • Food intake
  • Hepatic function
  • Metabolic rate
  • Urinary pH
  • Dosage (low vs. high)
  • Route of administration
  • Frequency of use
  • Duration of use
  • Use of other drugs

How to Safely Detox from Fentanyl

The only way to get fentanyl out of your system is to stop taking it and give your body time to metabolize and eliminate it. If you need to get fentanyl out of your system because you think you have taken too much or are at risk of an overdose, seek medical attention immediately. Signs of a fentanyl overdose include:

  • Dizziness
  • Confusion
  • Body weakness
  • Sleepiness
  • Hypoventilation
  • Blue-colored lips and fingernails
  • Unconsciousness or coma

Drug overdose can be fatal. If you suspect someone is experiencing an overdose, call 911 immediately. Do NOT be afraid to seek help. If you do not have access to a phone contact Web Poison Control Services for online assistance.

Fentanyl has a high risk of dependence. So, if dependence has formed and you stop taking it suddenly, you may experience fentanyl withdrawal symptoms. It’s important to consult your doctor about stopping taking fentanyl. Your doctor may prescribe other medications to help ease withdrawal symptoms and prevent breakthrough pain. In some cases, a medically supervised detox program may be needed.

Getting Help for Fentanyl Abuse

If you’re worried that you or a loved one are addicted to fentanyl, help is available. Contact us at The Recovery Village. We have a proven track record of caring and successful drug and alcohol addiction treatment.

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Editor – Jennifer Kopf
Jennifer Kopf is a Florida-based writer who likes to balance creative writing with helpful and informative pieces. Her passion for helping people has translated into writing about the importance of treatment for substance use and mental health disorders. Read more
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Medically Reviewed By – Dr. Kevin Wandler, MD
Kevin Wandler holds multiple positions at Advanced Recovery Systems. In addition to being the founding and chief medical director at Advanced Recovery Systems, he is also the medical director at The Recovery Village Ridgefield and at The Recovery Village Palmer Lake. Read more
Read Previous

CDC.gov. “Increases in Fentanyl Drug Confiscations[…] Overdose Fatalities.” October 26th, 2015. Accessed January 22nd, 2019.

CDC.gov. “Synthetic Opioid Overdose Data.” Accessed January 22nd, 2019.

CDC.gov. “Vital Statistics Rapid Release Provision[…]erdose Death Counts.” Centers for Disease Control and Prevention, October 13, 2021. Accessed October 14, 2021.

Drugabuse.gov. “Fentanyl”. June 2016. Accessed January 22nd, 2019.

Drugabuse.gov. “Emerging Trends and Alerts.” May 2018. Accessed January 22nd, 2019.

FDA.gov. “Fentanyl Patch Can Be Deadly To Children.” September 23, 2013. Accessed January 22nd, 2019.

Pubchem.gov. “Fentanyl”. Accessed January 22nd, 2019.

Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.