Medically Reviewed

How Long Does Fentanyl Stay in Your System?

- 8 sections

Medically Reviewed: September 25, 2019

Medical Reviewer

Chief Editor


All of the information on this page has been reviewed and verified by a certified addiction professional.

Fentanyl is a synthetic opioid that is used to treat moderate to severe pain. Healthcare professionals might prescribe transdermal patches of fentanyl to treat chronic pain conditions that cannot be managed by lesser opioids. That said, fentanyl is incredibly strong, being 50 to 100 times more potent than morphine.

The effects of fentanyl include drowsiness, euphoria, and slowed breathing. Many people abuse it to experience a potent high. Others might unintentionally consume fentanyl because it is used as an adulterant in other substances.

Most people who abuse fentanyl are buying it off of the street. The version of fentanyl found on the street is referred to as illegally manufactured fentanyl (IMF). Because it is not regulated by the FDA, there is no way to tell how potent it is.

Fentanyl has created a public health concern, as 70% of overdoses in 2022 involved synthetic opioids like IMF. If you or a loved one abuse fentanyl intentionally, you should seek support from a drug rehab program.

If you frequently misuse fentanyl you might be wondering how long it stays in your system. How long fentanyl remains in your body depends on the method of administration and whether you’ve been abusing it long-term. Keeping this in mind, IV fentanyl can stay in your system for 22 hours while patches or lozenges stay in your system for up to 36 hours.

How Long Does Fentanyl Stay in Your System?

Fentanyl is a prescription opioid that people abuse to experience a potent high. Understanding how long it stays in your system can prevent you from taking too much at once and experiencing a fatal overdose.

The half-life of fentanyl determines how long it will remain in your body. Even further, the half-life of fentanyl will depend on what method of administration you are using.

When fentanyl is taken intravenously, it has a half-life of 2 to 4 hours. It takes between 4 to 5 half-lives for a drug to leave your system. In other words, it takes between 11 to 22 hours to leave your system.

If you are using fentanyl patches or lozenges, the half-life is between 7 to 17 hours. This means it can take up to 36 hours to leave your system.

Factors that Affect How Long Fentanyl Remains in Your Body

How long fentanyl stays in your system varies depending on a variety of factors. One of the factors that plays a role in the amount of time fentanyl stays in your body is metabolism. Similar to how your body processes food, your metabolism affects the rate at which you eliminate drugs.

Other factors that affect how long fentanyl remains in your body include:

  • Route of administration (i.e., smoking, snorting, injecting, and more)
  • Frequency and duration of use
  • The dose of fentanyl you take
  • The speed of your metabolism
  • Age and weight
  • Body fat percentage
  • Genetics and sex
  • Water and nutrition intake
  • Liver and kidney functioning
  • Overall health
  • Whether you’ve consumed other substances

If you or a loved one abuse fentanyl, you should consider attending addiction treatment. Taking fentanyl when it is still in your system from previous use could result in a life-threatening overdose.

Does Fentanyl Show Up on a Drug Test?

Standard drug tests can detect natural opioids like morphine or heroin. Since fentanyl is synthetic, standard drug panels will not detect it. That said, specialized drug panels can be requested to determine whether you’ve abused fentanyl.

Even though fentanyl usually leaves your system within 24 hours, metabolites are left behind. These metabolites can be detected longer depending on which area of the body is being tested.


Urine tests are the most commonly used drug tests. Administrators prefer them because they are minimally invasive and relatively cheap. Keeping this in mind, fentanyl in urine can be detected for 24 to 72 hours after you use the drug.


Saliva tests are not used as commonly as urine tests because they are less reliable for a majority of drugs. When it comes to fentanyl, the results of saliva drug tests are inconsistent. Because of this, they are not used to test for fentanyl.


Doctors might use blood tests to detect fentanyl in your bloodstream. These tests can detect fentanyl for 5 to 48 hours after your last dose.


Hair tests are the most reliable form of drug testing out there. However, they can be expensive and tend to take long, which means they are not commonly used. Hair tests can detect fentanyl in your hair follicles for up to 90 days after your last dose.

Find Help for Fentanyl Abuse and Addiction

If you or a loved one regularly abuses fentanyl, it’s time to seek help. Fentanyl abuse can lead to life-threatening overdoses and long-term health concerns. Thankfully, addiction treatment programs can help you achieve long-lasting sobriety.

At PAX Memphis, we can connect you with a top-rated drug rehab program in your area. Whether you need detox for withdrawal symptoms or inpatient rehab, we can help you find a facility that suits your needs.

Contact us today for more information on finding fentanyl addiction treatment.