How Long Does Fentanyl Stay in Your System?

How Long Does Fentanyl Stay In Your System?

What is Fentanyl?

Fentanyl is an opioid most commonly prescribed to people who suffer from severe pain episodes. This drug is a Schedule II medication, which means that it has a high potential for abuse. Similarly to Morphine and Heroin, Fentanyl activates the receptors in the brain that are responsible for the sensation of euphoria. This dangerous substance is almost 50 times more potent than Heroin.

What are the Factors That Influence the Duration of Fentanyl’s Presence in Your System?


It is proven that older users tend to metabolize Fentanyl much slower than younger ones. According to Bentley and associates, drug elimination in the group of patients younger than 50 was 265 minutes, and in the panel of patients older than 60, it took 945 minutes.

Body type

Cheymol suggests that people with a higher percentage of body fat metabolize Fentanyl longer than users with low body fat index because they have less adipose tissue where Fentanyl can accumulate.

Liver function

Most of the Fentanyl is metabolized in the liver by the CYP3A4 enzyme. People suffering from cirrhosis or other hepatic conditions tend to eliminate Fentanyl at a slower rate than healthy individuals.

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Some people are genetically predisposed to metabolize Fentanyl much slower than others. Several alleles of CYP3A4 are responsible for poor Fentanyl metabolism.


Keeping in mind that most of the Fentanyl is eliminated through urine, it is clear that proper hydration can shorten the time needed for thorough elimination of the drug.

Metabolic rate


It is commonly known that people with higher basal metabolic rate (BMR) burn more energy during rest. Therefore, higher BMR can have a positive impact on Fentanyl excretion time.

Route of administration

There are three routes of Fentanyl administration—intravenous, transmucosal, and transdermal. For intravenous users, it takes 11 to 22 hours to eliminate Fentanyl from blood plasma.When it comes to transmucosal users, it takes up to 3.4 days to remove the drug, and for transdermal users, elimination time can last more than five days.

Dosage and frequency of use

The greater the dose of the Fentanyl, the more time it will take to excrete it from your system.

Combining Fentanyl with other drugs

Combining Fentanyl with other drugs, especially with CYP3A4 inhibitors, may have an adverse impact on fentanyl excretion.

How Long Does Fentanyl Stay in Your Blood/ Urine/ Saliva/ Hair?

Blood test for Fentanyl is conducted if a person can’t give a urine sample. A blood test can detect the presence of Fentanyl only minutes after the last dose. Also, the drug can be detected days after discontinuation.

A urine test is a non-invasive, safe way to determine whether someone is using Fentanyl. The drug can be detected quickly after the ingestion. Fentanyl is detectable through a urine drug test 3 days after the last dose.

The saliva test is rarely used in Fentanyl detection due to low accuracy.

Hair analysis provides a long detection window for Fentanyl, and it can detect the drug months after the last dose.

How is Fentanyl Metabolized?

25% of fentanyl is absorbed in a user’s mouth via buccal mucosa. The rest of the treatment (75%) is absorbed in the gastrointestinal tract. After the absorption, the drug is distributed in the heart, brain, kidneys, lungs, and spleen. Also, some of it can be deposited in the fat tissue. Fentanyl is metabolized in the liver by the CYP3A4 enzyme, and 90% of it is excreted in urine in the form of metabolites.

The Duration of Fentanyl Effects

Fentanyl taken intravenously reaches its peak 30 to 60 minutes post-injection, and analgesic effects kick in 7 to 15 minutes after ingestion. Effects of the drug start to fade away 1 to 2 hours after administration.

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How Long Does Fentanyl Stay in Your System?

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Comments 26

  • If a 50mcg transdermal fentynal patch is on a patient Monday 0600am removed Thursday 0600am, would the fentynal show up on a simple in-office urinalysis one week later? If a urinalysis were to be executed 7 days from the Thursday 0600am removal would the fentynal be detected?

    • I have fail for fentanyl 3 weeks aftwr last ise i only weight 135lbs but have kidney and liver damage, translation no one really knows how long it takes. I sought help for my addiction and quit cold turkey but because the stigma is 3 days i lost my kids for failing 7 days after admitting to use and co tinued to fail for 16 days

  • no you should be fine. Its like 3-4 days, but if you want to be safe drink lots of water. Just try not to flood your urine LoL

  • If fentanyl was found in a particular batch of heroin & patient used it intravenously on Friday 2:30pm will it show a positive result 5days later; given that the urine sample goes out to a lab to be dissected & specifically looks for it & its metabolites? This particular patient does have a higher BMI than normal range and has chronic HVC that thus far has not been treated for as of yet.

    • Angel.. if your test or this person’s is in 5 days. Just make sure you drink plenty of water and even coffee helps to get your urine flowing. Take a good multivitamin each day, and if you have it take 1000mg of vitamin c each day with your multivitamin..but if you don’t have that or even the multivitamin just make sure you drank at least four or five glasses of water a day and it will all be out of your system in 72 hours

  • After snoring one line of a f fentanyl after drinking five glasses of water for 2 days would it still come up as positive in a drug screen

  • Will fentanyl still come up as positive in urine 48 hrs after inhalation and drinking 5-7glasses of water for per day for said 48 hrs?

  • After last use of fentanyl by snorting will it be detected in urine 48 hrs later after drinking gallon of water and using multivitamin and vitamin c each day of 48 hr interval?

  • What are therapeutic range for a 100mcg patch?

  • I snorted 2 lines of fentanyl on Sunday and im drinking plenty of water and i always take vitamins and its been 8 days that next Monday and im still testing positive for fentanyl.i got boxes of urine tests and im still testing positive. I didn’t do alot and I’ve been drinking water why in the hell im still dirty wow its long.. help please im at my wits end thank u

    • It’s probably because of your body weigh, age etc. I don’t weigh too much. Only 148lbs. And it took around 9-10 days for it to leave my system. It’s weird to me and a bit annoying.

  • Angel, it’s the 12th of April. How long did it eventually take to leave your system?

    • I’ve done a fake Percocet Saturday 4/27 about half of it at 8 o clock. I have a test today 4/30 at 5 pm. I’ve been drinking a lot of water a Gatorade and cranberry juice. It’s about 70 hours. What are the chances of my urine being clean?

    • Fentynal,if I snorted some or had a patch on,about 6 days ago.If possible will or can it still read positive 6 days ago…

  • I took about half of a fake Percocet on Saturday 4/27 around 7-8 p. Not much, but I’m wondering if a lot of water and Gatorade would would make me come up negative on a ursine test Tuesday 4/30 at around 4 pm. Thaler be about 68 hours.

  • For anyone who want to know how long Fentanyl is in you its nine days give or take a day

  • is fentanyl detected in a mouth swab

  • I need to know. I used a 25 mcg patch. I put it on friday evening and took it off sunday evening. How long will it stay in my urine. I need to know

  • Yea its 9 to 10 days respectively

  • I failed a test after 7 days clean and my girl failed after 9 but we are overweight and it went to a lab

  • So if your overweight I would give it 10 days for a heavy user

  • I eas using heroin with fentanyl in it and on 4/26/19 hospalized for 12 days which i 2 surgeries 1 on the 30th which was the 2nd they used fentanyl im also in Methadone we get urined weekly its been over 30 days and im still testing dirty for fentanyl ( & methadone only – been clean since 4/26/19 ) whats the deal ?

  • (Continuation from 1st comment)
    Just so you have history I used heavily everyday for a 1 1/2 ( heroin w/fentanyl) and like I said ive been clean since 4/26/2019 Im very committed to my sobriety since i fell off the wagon ( more like jumped) after being clean for 4 yrs so im overweight, on Methadone ( 18yrs been on Methadone) do not have Hepatitis usually it takes 2 wks or so to get clean urine , swab or blood but like I said im recovering over 2 surgeries 1 skin graph on right extremely painful ( all of which ive chosen to do with NO pain pills 2nd surgery on my arm then 3 days after i got ho.e broke my foot same leg w/ graph ( still NO pain piils ) but i get tested weekly @ and im clinic still Fentanyl dirty what in the world im inactive but drink a s**t load of green tea methadone slows your metabolism but really no wonder im having such a hard time losing weight its been over a month my 2nd surgery was on 4/30/2019 …
    .does anyone have any suggestions because im at a loss they keep telling me fentanyl stays in your system 4 days WTF i dont use anything and theres nothing worse than being told you r using when im not im 49 yrs old if I want to use I will PERIOD but heres the I don’t i fell off tve wagon after my husband died unexpectedly after I got out of the bed for 30 minutes came back he was dead devastated me and I took the easier way out then having to deal with what I was feeling but enough about that i dont know what to do they want to cut my dose in half if im not clean from fentanyl within a certain time limit but how do i do that ive never even seen fentanyl i just dont know what to do HELP !!!!!

  • I’ve been a heavy user intravenous if fentanyl for years been clean for 7 days drinking lots of water still dirty urine I’m 28 I’m 5’8-5’9 and 160 pounds

  • Has anyone experienced this I took a druge test every other day I popped for fentanyl after being clean for 21 days finally on the 22nd day it was completely negative

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