How Long Can Fentanyl Be Detected in Your System?

A person injecting a syringe on her stomach

Fentanyl is commonly used to treat severe pain. However, fentanyl is also used illicitly for purposes other than medical. With fentanyl abuse on the rise, the biggest question is, how long can fentanyl be detected in your system?

I’ve talked with a friend doctor, checked the studies on fentanyl use, and used fentanyl myself. Today, I’ll explain what this substance is and how long tests can detect it.

Summary of the Key Findings

  • Fentanyl is a strong opioid that can be detected for up to 72 hours.
  • Fentanyl can be detected on different tests. A hair test can detect illicit fentanyl use for up to three months.
  • You can calculate the half-life of fentanyl to know how long it’ll stay in your system.

What Is Fentanyl?

A close up shot of an inside of a pill bottlFentanyl is a prescription opioid used for severe pain. It’s commonly used in advanced cancer or chronic pain cases when patients are tolerant to less potent synthetic opioids. 

Fentanyl is 50 to 100 times stronger than morphine [1]. It comes in several forms: lozenge, tablet, nasal spray, transdermal patch, and injections. 

However, data shows that fentanyl addiction has been on the rise in recent years. Opioid overdose deaths rose more than 16% from 2018 to 2019  [2]. 

“Some drug dealers are mixing fentanyl with other drugs, such as heroin, cocaine, methamphetamine, and MDMA. This is because it takes very little to produce a high with fentanyl, making it a cheaper option. This is especially risky when people taking drugs don’t realize they might contain fentanyl as a cheap but dangerous additive. They might be taking stronger opioids than their bodies are used to and can be more likely to overdose.” – National Institute on Drug Abuse

Illegal fentanyl comes in the form of powder, tablets, mixed with other drugs and opioids, or spiked on blotted paper.

Because fentanyl is so powerful, there’s a high potential for addiction and abuse. 

How Long Does Fentanyl Stay in Your System?

Fentanyl stays in your system for up to 72 hours [3]. You can feel fentanyl for only a few hours, but drug traces stay in your system for much longer.

How long fentanyl stays in your system also depends on several factors:

  • Someone checking for blood sugarDose
  • Frequency of use
  • Use duration
  • Administration method
  • Metabolism speed
  • Your weight
  • Age
  • Gender
  • Kidney and liver functioning
  • Urine concentration 

A thorough drug test detects fentanyl from 24 to 82 hours after last use. Norfentanyl, a metabolite created when fentanyl breaks down in the body, can be detected for up to 96 hours or even three months in hair tests [4].

1. Urine Test

Yellow liquid inside a bottleUrine drug tests are the most common kind of drug testing employers use. This drug test can detect fentanyl between 1 to 3 days after use. 

In some cases, fentanyl can be flushed out of the system in the first 24 hours after taking it. However, an advanced urine drug test can detect the metabolite norfentanyl between 46 to 96 hours.

Also, how long fentanyl stays in the system depends on the frequency of use. If you’ve used it for long periods, it can be stored in fat and detected by urinalysis between 7 and 13 days.

2. Blood Test

Fentanyl will show up on a blood test between 5 and 48 hours after the last use [5]. Blood tests aren’t considered very effective for fentanyl detection because this substance doesn’t usually stay in the blood for more than 12 hours. 

Fentanyl is absorbed from the blood by other organs, which means it’s present in the body but not in the blood. 

3. Hair Test

A doctor checking someone's hairA hair test isn’t commonly done because it’s more expensive compared to other tests, but it can detect fentanyl or other opioids for up to three months after the last use [6]. 

You can test positive on a hair test because hair grows slowly and can give a good health history timeline compared to other standard drug tests. 

One drawback of hair tests, even advanced ones, is that they can’t determine how long ago fentanyl was used. For example, if a patient was given fentanyl after surgery, this isn’t opioid abuse. Still, a thorough hair test will definitively show fentanyl use.

4. Saliva Tests

Saliva tests aren’t considered an effective way to check for fentanyl opioid addiction. This is because saliva tests can’t consistently detect fentanyl or its metabolites [7].

What Does It Do to the Body?

Fentanyl affects the body by suppressing central nervous system functions, such as breathing and heart rate, and temperature regulation.

Fentanyl increases the chemical dopamine, which is responsible for our feelings of pleasure, which results in the feeling of relaxation and happiness. This is why there’s a high rate of fentanyl addiction. After extended fentanyl use, the opioid receptors in the brain adjust to this feeling of pleasure, which is why there’s breakthrough pain if users suddenly halt the opioid use. Moreover, many users need addiction treatment to deal with withdrawal symptoms.

Fentanyl withdrawal symptoms include:

  • A woman about to pukeCramps
  • Nausea
  • Vomiting
  • Diarrhea
  • Irritability
  • Anxiety
  • Tremors
  • Fatigue
  • Restlessness 
  • Rapid heart rate
  • Muscle spasms
  • Difficulty feeling positive or pleasure
  • Drug cravings

The only way to remove fentanyl from your system is to stop taking it. However, due to all the withdrawal symptoms that follow long fentanyl use, it’s best to seek professional medical advice and get prescribed addiction treatment. 

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How to calculate how long fentanyl stays in the system?

You can calculate how long fentanyl stays in your system by the half-life of elimination. Elimination half-life refers to how long it takes for half of one dose of any kind of drug to be removed from the body [8].

How Long Does Fentanyl Stay in Your Body?

Fentanyl stays in your body for as long as 72 hours. It is a strong opioid commonly used to treat people in pain. However, it’s highly addictive, and there are increasing deaths due to fentanyl abuse.

If you or your loved one abuse fentanyl, you should seek medical attention immediately. Professionals at treatment facilities can provide help with a substance use disorder.

If you have a work test coming up and aren’t sure if fentanyl will be detectable in your system, you can estimate the half-life to calculate fentanyl presence.

Visit our site to learn about detox drinks and how they can help you pass a test.










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