How Long Does Fentanyl Stay in Your System

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Fentanyl is a potent prescription opioid used to manage moderate to severe pain. The prevalence of fentanyl abuse has sharply risen in recent years, potentially leading to increased associated overdoses and death tolls. Many people who routinely abuse this drug or wish to stop using it often want to know how long it stays in the system and what determines this value. This information can not only help them maintain safe levels of this drug in their bodies but also allow them to safely detox from it with minimal consequences.

An Overview of Fentanyl Use and Abuse

Fentanyl is a manmade opioid drug prescribed to treat moderate to severe pain associated with cancer. It is also a beneficial drug to maintain breakthrough pain that does not respond to other less-potent alternatives. With up to 100 times higher potency than morphine, fentanyl is available in different forms, such as tablets, nasal sprays, injectable solutions, and lozenges. Illicitly, it is also available in powdered and tablet form in addition to being available as spiked on blotter paper.

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To the easy availability of fentanyl, its use, abuse, and overdoses are becoming more common every day. In the year 2017, the United States reported more than 28,000 deaths due to synthetic opioid overdoses. The death toll associated with opioid use is on the rise and statistics indicate that these overdoses are primarily driven by fentanyl, especially its illicit varieties.

Factors Determining Fentanyl Detection Time

Several factors affect how long fentanyl stays in a person’s system once they take it. Some of these factors include the following:


Fentanyl has a slow rate of clearance in people belonging to older age groups.


Some people are genetically deficient in breaking down and metabolizing fentanyl due to the absence of an enzyme called CYP3A4.

Weight, body mass, and body fat

People with a high body fat percentage generally retain fentanyl for a longer duration of time than those with a lesser fat percentage.

Liver function

People who suffer from liver disease or reduced liver function may eliminate this drug slower than those with normal liver function.

Method of consumption

Different methods of consumption lead to different fentanyl clearance rates. For example, intravenous injection of this drug leads to faster elimination.


The higher the dose, the longer the drug stays in the body.

Frequency and duration of use

The duration of fentanyl use along with the frequency with which a person is taking it can also increase or decrease the elimination rate of this drug.

Polysubstance use

A person using fentanyl with alcohol or other substances may require a longer time duration to eliminate fentanyl from their system.

Fentanyl Methods of Use

To determine precisely how long fentanyl stays in the system, it is imperative to familiarize yourself with different ways of using the drug.

Intravenous Fentanyl

Some people prefer injecting fentanyl liquid directly into their veins. This method of consumption is the best for achieving the quickest results. For example, it may provide relief from labor pains within seconds.

Oral Fentanyl

Oral fentanyl comes from tablets that an individual can place between their tongue and cheek and wait until it dissolves. Sometimes, people may crush the pills and snort the powder or inject it for quicker results.

Transmucosal Lozenges

This form of fentanyl is available as hard drops people put in their cheek pockets or under their tongues. As the lozenges begin to dissolve, the medication quickly absorbs into the soft tissue of the oral cavity from where it enters the bloodstream at a fast rate.

Transdermal Patch

This patch can be applied to the skin for slow and steady absorption of fentanyl into the bloodstream over time.

What all of these methods have in common is that they help move fentanyl into the bloodstream at different rates. These rates ultimately impact how long fentanyl stays in the system and how long until the body starts eliminating it.

Fentanyl Duration Time According to Method of Consumption

How long fentanyl stays in your system also depends on your preferred method of consumption. For example:

Eating Fentanyl

People who use fentanyl orally, such as in pill form, may take up to two days to completely leave the digestive system. The effects of the medication may disappear within two to four hours of taking it. Remember that even after fentanyl has left the digestive system, some drug tests may still pick it up.

Smoking Fentanyl

People who smoke fentanyl start experiencing its effects almost immediately. These effects may linger on for 30 to 60 minutes only, but a drug test may pick up its presence for days to come.

Using Fentanyl Patch

The fentanyl released from a patch may remain in the system for up to three days after you remove it.

How Long Does Fentanyl Stay in Your System?

The answer to how long fentanyl stays in your system varies depending on the type of drug test used to detect it.

How long does fentanyl stay in urine?

When an individual uses fentanyl, it breaks down into two different metabolites that a drug screen can easily detect. In case of a urine test, you may test positive for these metabolites within two hours of using fentanyl until three days following the last dose.

How long does fentanyl last in blood?

While a urine test remains the preferable choice for a drug screen, many experts resort to blood testing, especially in cases where a urine test is not possible. Depending on the half-life of fentanyl, a blood test may detect its intravenous for up to 20 hours and oral form for up to 3 days. A transdermal patch may be tested up to 3.5 days after removal.

How long does fentanyl stay in your saliva?

It can be challenging to detect fentanyl in a person’s saliva, especially if they consume the drug in an intravenous or transdermal form. While saliva test is not really in use these days, research suggests that the drug becomes undetectable in saliva after 24 hours of use.

How long does fentanyl stay in hair?

Hair testing remains one of the most reliable ways of confirming past fentanyl use. While the test may take a few days to complete and give results, it can accurately detect fentanyl traces if you have used the drug during the past 90 days.


What does fentanyl look like?

The legal or medical forms of fentanyl include liquid, patches, lollipops, or lozenges. Illegal drugs usually come in powdered form with light brown or ivory hues. Even if you know exactly what fentanyl looks like, it may not be easy to spot the medication as it is often mixed with other substances.

What does fentanyl taste like?

Fentanyl does not have a discernable taste, so it may make it difficult to tell if you are using it. Many users describe it as having a sweet taste in contrast to heroin with its characteristic bitter taste. Others believe it to be tasteless on its own with the sweet taste coming from the liquid that is often mixed with fentanyl. Hence, it is impossible to detect this drug solely based on its taste.

What makes fentanyl so dangerous?

Fentanyl is a highly potent drug with up to 100 times more strength than other opioids like morphine. Many manufacturers mix it with heroin as it becomes easier to produce and obtain and induces a much more powerful euphoria. Using heroin without knowing that it also contains fentanyl can put anyone at a very high risk of an overdose and potential drug poisoning.

Fentanyl quickly acts on the opioid receptors in the brain to aggressively release dopamine in high amounts. This increased amount of dopamine triggers imbalances in the central nervous system while depressing respiratory processes. Due to these dangerous side effects, the death toll associated with fentanyl use and abuse is on the rise. The FDA has classified it as a Schedule II drug with a very high potential for dependence and abuse.

Why do people conduct fentanyl drug tests?

There are several reasons why someone would conduct a drug test to screen for fentanyl or other substances, such as the following:

  • Some employers make it mandatory to appear in and pass a drug test before hiring new employees. These drug tests may continue periodically throughout the length of their employment for better monitoring of drug use
  • Healthcare professionals may conduct blood tests to make sure that a patient is using fentanyl in the right dose
  • Such drug tests may also become necessary in many legal situations that warrant investigations, such as a car accident or crime.

What is the half-life of fentanyl?

The half-life of fentanyl is usually between three to seven hours. Half-life refers to the time it takes a medication to reduce its quantity by half. In the case of fentanyl, this time duration may vary depending on a user’s current liver health. The half-life of the drug matters because if it is shorter, it means the drug is more likely to cause withdrawal symptoms.

Can fentanyl use lead to overdose? What are the symptoms?

Overdose is one of the most severe risks associated with fentanyl use, especially in people using it with other substances. Some common symptoms of a fentanyl overdose include the following:

  • Slowed breathing
  • Vomiting
  • Going limp
  • Pinpoint or constricted pupils
  • Grayish or blue skin
  • Cold, clammy skin
  • Low blood pressure
  • Gurgling sounds

Keep in mind that a fentanyl overdose may differ from other types of opioid overdoses as its symptoms are quicker to show, usually within minutes after consuming it.

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