How Long Does Fentanyl Stay In Your System?

Written by Abby Doty

& Medically Reviewed by Dr. Jessica Pyhtila, PharmD

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Last Updated - 10/28/2022

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Updated 10/28/2022

Fentanyl is one of the most potent opioids medically available in the United States. Prescribed to treat severe pain, its analgesic effects can help a person struggling to get their pain under control. It is also misused illicitly and is sometimes mixed into other substances. But how long fentanyl lasts and how long it stays in your body can vary based on several factors. For this reason, it is important to know what elements determine how long fentanyl stays in your system.

How Long Do the Effects of Fentanyl Last?

Fentanyl comes in several different formulations, and the drug can last different lengths of time depending on which formulation is used. This is important because the duration of fentanyl’s effects often impacts how many doses per day a doctor prescribes for you.

Fentanyl dosage formDuration of effect
Injectable (given in hospitals only)30 to 60 minutes
Lozenge4 hours
Intrabuccal tablet4 hours
Sublingual tablet2 hours
Sublingual spray4 hours
Nasal spray2 hours
Transdermal patch72 to 96 hours

Fentanyl Half-Life

The half-life of a drug refers to how long half of a dose lasts in your body before it is eliminated. In the case of fentanyl, the liver is the main place where fentanyl breaks down using an enzyme called CYP3A4. The drug is then removed from the body in the urine.

Fentanyl’s half-life varies depending upon the dosage form used. Generally, it takes five half-lives to remove a drug from your system completely. Therefore, half-lives can help you predict how long traces of fentanyl may remain in your body.

Fentanyl dosage formHalf-life
Lozenge3.2 to 6.4 hours
Intrabuccal tablet2.6 to 11.7 hours
Sublingual tablet5 to 13.5 hours
Sublingual spray5.3 to 12 hours
Nasal spray15 to 25 hours
Transdermal patch20 to 27 hours

In the case of a fentanyl lozenge, a half-life of up to 6.4 hours means that traces of the drug would remain in your system for up to 32 hours, or roughly five half-lives.

Does Fentanyl Show Up on a Drug Test?

Fentanyl shows up on some drug tests. However, the drug does not readily show up on many standard drug tests, and special, fentanyl-specific tests need to be ordered. This is due to fentanyl’s chemistry. As a synthetic, or lab-made, opioid, it has slightly different biochemistry compared to many other opioids like morphine or heroin.

How Long Does Fentanyl Stay In Your Blood?

Fentanyl is detectable in blood and plasma (the liquid component of blood) for anywhere between three and 12 hours after the last dose. Fentanyl’s breakdown product norfentanyl is also detectable for nine and ten hours.

How Long Does Fentanyl Stay In Urine?

Fentanyl and its breakdown product norfentanyl are detectable in urine for up to three days after the last dose.

How Long Does Fentanyl Stay In Your Hair?

A 1.5-inch hair sample can show if any fentanyl was used within the previous 90 days.

How Long Does Fentanyl Stay In Your Saliva?

Fentanyl is detectable in saliva for up to two days after the last dose.

How Long Does Fentanyl Stay In Your Breast Milk?

Factors That Affect Fentanyl Detection Times

Fentanyl may have different detection times in different people. This is because multiple factors can influence the tests, including:

  • Fentanyl dose: A higher dose may be detectable for a longer time than a smaller dose.
  • Frequency of fentanyl administration: If you take fentanyl more often, it may be detectable for longer than if you take it only occasionally.
  • Fentanyl formulation: Taking a fentanyl formulation with a long half-life like transdermal fentanyl may keep the drug detectable in your system longer than a formulation with a shorter half-life.
  • Age: Older people tend to eliminate fentanyl from their systems slower than younger people.
  • Kidney function: People with kidney problems often clear fentanyl from their systems more slowly than people with healthy kidneys.
  • Drug interactions: Medications that impact CYP3A4, the main enzyme that breaks down fentanyl, may make the drug last shorter or longer than expected.

Fentanyl Addiction Treatment & Detox in Colorado

If you or a loved one struggles with fentanyl abuse, your addiction may seem like an insurmountable obstacle. But recovery is possible with help. Our fentanyl recovery experts at The Recovery Village at Palmer Lake can help you quit fentanyl for good. Our medical detox program can help your body rid itself of fentanyl safely, while our inpatient and outpatient rehab options can teach you the skills to stay fentanyl-free for life. Don’t wait: contact us today.


Hallare, Jericho & Gerriets, Valerie. “Half Life.” StatPearls, August 23, 2021. Accessed May 24, 2022.

Gryczynski, Jan, et al. “Hair Drug Testing Results and Self-repor[…]isk Illicit Drug Use.” Drug and Alcohol Dependence, May 17, 2014. Accessed May 24, 2022.

ARUP Laboratories. “Drug Plasma Half-Life and Urine Detection Window.” October 2021. Accessed May 24, 2022.

Cansford Laboratories. “Oral Fluid (Saliva) Testing.” Accessed May 24, 2022.

ARUP Laboratories. “Therapeutic Drug Monitoring.” June 2021. Accessed May 24, 2022. “Fentanyl.” March 3, 2022. Accessed May 24, 2022.

ARUP Laboratories. “Drug Testing.” March 2022. Accessed May 24, 2022.

Drugs and Lactation Database. “Fentanyl.” May 15, 2022. Accessed May 24, 2022.


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