How Long Does Fentanyl Stay in Your System?


When taken intravenously, fentanyl has an elimination half-life of approximately 2 to 4 hours in adults, meaning it takes approximately 11 to 22 hours to completely leave your system.


Although many people had never heard of fentanyl before it claimed the life of the musician Prince in April 2016, this synthetic opiate pain reliever is one of the strongest opiates available today. It’s 50 to 100 times more potent than morphine. As a result, it’s often used to relieve severe pain, especially after surgery, during cancer treatment, and to manage breakthrough pain.

In its prescription form, fentanyl is known by names such as Actiq, Duragesic, and Sublimaze. However, many people obtain fentanyl without a prescription on the black market. When used for recreational purposes, fentanyl typically comes in the form of powder, spiked on blotted paper or mixed with heroin, cocaine or other street drugs to amplify the potency.

Fentanyl abuse is dangerous and even deadly. In March 2015, the Drug Enforcement Agency (DEA) issued a nationwide alert identifying fentanyl as a threat to public health and public safety.

To determine how long fentanyl will stay in your system after you stop taking it, it’s important to consider its elimination half-life. Elimination half-life refers to how long it takes for half of a single dose of a drug to leave the body.

The elimination half-life of fentanyl is subject to some variation based on the method by which it’s administered. When taken intravenously, fentanyl has an elimination half-life of approximately 2 to 4 hours in adults, meaning it takes approximately 11 to 22 hours to leave your system.

If you use the patch or lozenge, fentanyl exhibits a half-life of approximately seven hours, and it will take around 36 hours for the drug to completely leave your system after you stop using.

As fentanyl breaks down in your system, it leaves behind traces called metabolites. These metabolites stay in your system longer, meaning that a thorough drug test could detect fentanyl in your system even several days after you stop taking it.

While often undetected by standard drug tests, an advanced urine drug test can be used to identify fentanyl. In this case, fentanyl can be recognized in urine for eight to 24 hours, depending on a variety of factors including age, weight and more. While fentanyl may not be recognized by urine tests after a full day, it can still be detected by other methods and continue to wreak havoc on the body after improper use.
Hair is one of the most telling features of a person’s health. Because of its relative slow growth process, it is often one of the most accurate timelines of health history. For this reason, hair drug testing can be one of the most effective and telling signs of long-term drug use. Fentanyl can be detected in hair for up to 90 days, about three months.
Blood testing is one of the least effective methods of detecting drug use over a long period of time. Fentanyl can only be recognized in the bloodstream for up to 12 hours. Although it typically isn’t detectable in the blood for longer than half a day, the negative side effects of long-term opioid use manifest themselves in a variety of ways, including life-threatening addiction and potential overdose.
Saliva can be used for a variety of tests — from DNA to drug testing, doctors may take a saliva swab or spittle sample to learn more about a patient. Saliva drug tests are are often more accurate than urine or blood tests as they can detect fentanyl for one to three days after use.
There are a variety of factors that influence how long fentanyl stays in your system after your last dose. Some of these variables include:
  • Age
  • Weight
  • Height
  • Body mass
  • Body fat
  • Genetics
  • Food intake
  • Hepatic function
  • Metabolic rate
  • Urinary pH
  • Dosage (low vs. high)
  • Route of administration
  • Frequency of use
  • Duration of use
  • Use of other drugs
Although fentanyl is much stronger than other opiates, it’s not commonly tested for on standard drug tests, which often aim to detect the presence of opioids that metabolize into morphine. Since fentanyl doesn’t metabolize into morphine, it’s unlikely to be detected unless an advanced drug test is ordered. However, if an advanced drug test is ordered, fentanyl is easily detected through urine, hair, saliva, and blood tests. Fentanyl can be detected in urine for eight to 24 hours, in blood for up to 12 hours, in saliva for one to three days, and in hair for up to 90 days.
There are treatment facilities that offer rapid detox from fentanyl, which typically includes anesthesia-assisted withdrawal. During rapid detox, the patient is sedated and put into immediate medical withdrawal by using an opiate blocker, such as naltrexone. It’s important to understand, however, that rapid detox is often dangerous and ineffective. Several studies have shown that this method does not result in less discomfort compared to any other methods of fentanyl withdrawal.
As a schedule II prescription opiate, fentanyl has a high potential for abuse. It’s one of the strongest opiates on the market and is more potent than both heroin and morphine. Since fentanyl works to eliminate all the pain in the body and produces a powerful high, a person can easily become addicted to fentanyl. Individuals who abuse fentanyl often seek the euphoric effects produced by the drug. In some cases, a person may start using fentanyl as prescribed by their doctor, but then it turns into a situation where they continue taking it for non-medical reasons. The signs and symptoms of fentanyl abuse include:
  • Confusion
  • Depression
  • Difficulty walking
  • Muscle stiffness
  • Slowed heart rate
  • Labored breathing
  • Weakness
  • Dizziness, lightheadedness, and fainting
  • Shaking
  • Sleepiness
  • Slurred speech
  • Nausea and vomiting
  • Itching and scratching
  • Pinpoint pupils
How Long Does Fentanyl Stay in Your System?
4.5 (90%) 2 votes