How Long Does Fentanyl Stay In Your System?

Last Updated: February 6, 2024

A potent synthetic opioid, fentanyl is anywhere from 50 to 100 times stronger than morphine. A prescription drug, fentanyl, is also increasingly made in illegal labs and sold on the streets. Between December 2020 and December 2021, more than107,000 overdose deaths were reported in the U.S., primarily driven by illicit fentanyl, along with methamphetamine and cocaine. So how long does fentanyl stay in your system, and what else should you know about this dangerous and often deadly drug?

How Long Does Fentanyl Last?

In a medical setting, fentanyl can be given as a shot or in a patch on the skin. Fentanyl’s also prescribed as a lozenge similar to a cough drop. Illegal fentanyl is more often sold as a powder, put in eye droppers and nasal sprays, dropped on blotter paper, or made into pills that can look like other prescription opioids.

  • When someone uses fentanyl, it binds to opioid receptors. 
  • Opioid receptors are in the parts of the brain controlling emotions and pain.
  • After someone repeatedly takes opioids, tolerance develops meaning that higher doses are required to produce the same effect
  • This makes it hard to feel pleasure from anything besides opioids, leading to addiction and dependence.

If someone takes fentanyl as a tablet, lozenge, or nasal spray, it will usually take effect within 15-30 minutes. The effects will often wear off in around four to six hours, but the drug can show up in the system for much longer. If someone uses a fentanyl patch, it can take a day or two to begin showing effects, but they last longer. If someone uses fentanyl intravenously, its onset of action can be less than 60 seconds, with peak effects in two to four minutes.

Half-life of Fentanyl

The half-life of fentanyl is anywhere from three to seven hours. A drug’s half-life is how long it takes for the amount of the active substance to reduce by half in your body. The half-life of fentanyl and other drugs varies depending on your body’s processes and elimination.The half-life of fentanyl is important because when it’s shorter, like with fentanyl, it means more withdrawal issues can occur.

Fentanyl Drug Testing

One of the most common reasons for fentanyl drug testing is employment. Drug testing may also be done in medical settings, as part of addiction treatment programs, by family members, or as part of the criminal justice system, such as a probation requirement. A fentanyl drug test isn’t included on the standard 5-panel test employers often use. A specialized drug test for fentanyl must be ordered.

Also, one of the issues currently facing the United States is the fact that fentanyl is being added to other drugs, including cocaine, MDMA and fake Percocet pills obtained online. Even small amounts of the fentanyl contained in these drugs are fatal and are responsible for a rising amount of overdoses and deaths. Fentanyl test strips are available to buy so that drugs can be tested to ensure there is no fentanyl in them.

Factors That Affect Fentanyl Detection Times

Many variables affect how long fentanyl will stay in your system after you take it. Some of these factors that affect fentanyl detection times include:

  • Age: Fentanyl typically has a lower clearance in elderly patients.
  • Weight, body mass and body fat: People with a higher percentage of body fat are likely to retain fentanyl for longer than those with less body fat. This may be because fentanyl is redistributed to fat tissue.
  • Genetics: Fentanyl is metabolized by CYP3A4 enzymes primarily. Some people may be unable to efficiently metabolize the drug because of poor enzyme function.
  • Liver function: If someone has poor liver function, they are likely to eliminate fentanyl more slowly than people with normal hepatic function.
  • The dose used: The higher your dose, the longer you might expect fentanyl to stay in your system.
  • How fentanyl was used: Using fentanyl intravenously tends to lead to the fastest elimination time.
  • How often it’s used and for how long: The duration of fentanyl use and how often you use it can make it stay in the system longer.
  • Whether other drugs are used: If someone uses other drugs simultaneously with fentanyl, it may affect its metabolism, which can affect its half-life.

How Long Does Fentanyl Stay In Your Urine?

When someone uses fentanyl, it breaks down into two metabolites detected in the drug screen. Fentanyl and its metabolites can show up in urine within two to three hours of using the drug. They can continue to show up in a urine screen for one to three days after using it just one time.

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How Long Does Fentanyl Stay In Your Blood?

Blood testing might be used if someone can’t be tested using a urine screening for fentanyl. It’s rare to test for drugs with a blood test because they are considered invasive. Based on its half-life, blood testing can detect IV fentanyl for up to 20 hours, oral fentanyl for up to 3 days and transdermal fentanyl (patch) for up to 3.5 days.

How Long Does Fentanyl Stay In Your Saliva?

It’s challenging to detect fentanyl in saliva samples, especially if someone takes it transdermally or intravenously. In a study of participants receiving fentanyl, saliva tests did not show the presence of fentanyl or any of its metabolites at 24 hours or after; therefore, this test is not really used to detect fentanyl.

How Long Does Fentanyl Stay In Your Hair?

Hair testing can be a reliable way to detect past fentanyl use and fentanyl analogs, and other synthetic opioids. The downside of a hair test for fentanyl is that it can take a few days to show use initially, but after that point, it can show fentanyl use for up to 90 days.

Get Help for Fentanyl Addiction in Orlando, FL

Opioid withdrawal from drugs, including fentanyl, can be life-threatening.  A medically supervised detox program can help you safely and successfully withdraw from fentanyl and other substances. Certain medicines can be used during this time to reduce the severity of your withdrawal symptoms if you’re dependent on opioids. With a safe, supervised withdrawal program, you can transition to addiction treatment. We encourage you to contact our team at Orlando Recovery Center. We offer a state-of-the-art, evidence-based detox and addiction treatment program in Central Florida.

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Vahedi, Hojat Sheikh Motahar; et al. “Comparison between intravenous morphine […]imb traumatic injury.” World Journal of Emergency Medicine, 2019. Accessed August 10, 2022.

Ramos-Matos, Carlos F; Vistas, Karlyle G; Lopez-Ojeda, Wilfredo. “Fentanyl.” StatPearls, May 30, 22. Accessed August 7, 2022.

MindInfo. “Psychiatric Medication: What is a drug’s half-life?.” March 2021. Accessed August 7, 2022.

National Drug Screening, Inc. “An Overview of the Fentanyl Drug Test.” Accessed August 7, 2022.

NYC.gov. “How to Test Your Drugs Using Fentanyl Test Strips.” Accessed August 10, 2022.

Arnold, Ashlee. “How Long Does Fentanyl Stay In Your System?” U.S. Drug Test Centers, January 26, 2022. Accessed August 7, 2022.

Kuip, Evelien, J.M. et al. “A review of factors explaining variabili[…] for cancer patients. “British Journal of Clinical Pharmacology, February 2017. Accessed August 7, 2022.

Silverstein, J H; et al. “An analysis of the duration of fentanyl […] in urine and saliva.” Anesthesia and Analgesia, March 1993. Accessed August 10, 2022.

Sevarino, Kevin A MD, Ph.D. “Medically supervised opioid withdrawal d[…]atment for addiction.” UpToDate. January 2022. Accessed August 7, 2022.

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