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Will Flexeril show up on a routine urine tox screen?

This question has also been asked and answered here: Will Flexeril (cyclobenzaprine) show up on a drug test?

14 Answers

UANurse 23 March 2020

I administer hundreds upon hundreds of drug tests on a monthly basis and never has an employer asked us to look for Flexeril aka cyclobenzaprine. If the medication is prescribed to you there is never a problem just bring your bottles to your UA testing. I have been doing this for 11 years and never have I had an employer care if your on any antidepressants or muscle relaxers!

Votes: +1
Shan728 23 Jan 2020

I’ve worked in the medical field for 20+ years as a nurse, and just went to my doctor yesterday for an appointment. I am also prescribed Flexeril and had a urine test done. What do you know, I came back positive for tricyclics. As a nurse, I will tell you one thing: I do NOT take any scripts that are not mine, and I do NOT take any antidepressants. Flexeril is one of those medications that can make a UA come back “presumptive positive” for tricyclics, even though it is a not a tricyclic anti-depressant
So to answer your question, yes it can definitely come back on a tox screen as a tricyclic.

Votes: +0
Tmford2000 1 Jan 2020

I’m sorry but all of you are misinformed. Flexeril is a muscle relaxant (cyclobenzaprine is the generic name). It is not a narcotic. However in some cases it will cause a FALSE positive for tricyclic antidepressants but in most cases will not. Most drug screens for employment or law agencies don’t test for antidepressants unless you are suppose to be taking them.

Votes: +0
Rowdy Ron 9 Jan 2018

Lol, i guess this isn't the place to get answer's. Too many say yes, too many say no. Which one is it?

Votes: +1
Parb 7 June 2019

This is the best response to this question

masso 2 June 2017

Just to educate not judge:

Flexeril (Cyclobenzaprine) belongs to the drug of class skeletal muscle relaxants.

Cyclobenzaprine – Can Cause False Positives For Tricyclic Antidepressants

I know it for a fact.

Votes: +2
masso 2 June 2017


" Several other substances also cause false-positive tricyclic antidepressant toxic screen results, including certain antipsychotic medications, antihistamines, and the muscle relaxant cyclobenzaprine. Specific tests and drugs causing false-positive results are presented in table form."

SOURCE: National Institute of Health.-US Library of Medicine.

Toisoldier2000 2 June 2017

I just took Flexeril. I tested myself with 12 panel and came back positive for barbiturates

Votes: +0
Punk1234 12 June 2017

This makes no sense? It's not even close to a barbiturate (Xanax, Ativan, Klonopin). So you were certainly doing something else with it??


Xanax, Valium, Klonopin, Versed, Ativan and such are all benzodiazipeims not barbiturates. Had to clear that one up

Tmford2000 1 Jan 2020

Sounds like you took some barbiturates recently. Flexeril tests false positive for antidepressants because they are similar but not for barbiturates??

Barb0109 4 Nov 2016


Votes: +0
jdaum 4 Jan 2015

According to the Medscape app under flexeril and the pharmacology tab it states:

"Structurally related to cyclic antidepressants, and pharmacologic effects are similar, including reserpine antagonism, norepinephrine potentiation, potent peripheral and central anticholinergic effects, and sedation; reduces tonic somatic motor activity influencing alpha and gamma motor neurons"

This leads me to believe you could get a false positive for tricyclic antidepressants, which are potentially fatal if overdosed...

Votes: +0
cooperslady 21 Sep 2014

I was just prescribed flexeril for a pinched nerve in my back. I do weekly drug screens for my doctor. And antidepressants showed up in my test. After my urine was dent to a lab, it came back as my prescribed flexeril. So yes it does show up in a test. But its non-narcotic. It falls under category of antidepressants.

Votes: +1
Mike Curtis 13 Dec 2014

No... it doesn't. Stop spreading misinformation.

mudplayerx 10 Jan 2018

Mike, Flexeril is a common cross reactant with TCA’s in drug tests. I think you are the one that should stop providing misinformation.

Koljohnson07 29 June 2018

Yup, original poster is correct. It will show up due to cross reactivity to TCAs during screening and will come back negative for confirmation unless the office specifically asks to add cyclobenzaprine to the list should the patient screen positive for TCAs. TCAs are being routinely checked now as many POC cups come with the screen built into them. Many work place testing will only confirm TCA and not cyclobenzaprine though. TCAs are an antidepressant but they are also abused.

Tmford2000 1 Jan 2020

It’s not an antidepressant but can cause a false positive for antidepressants. I work in a drug and alcohol treatment facility and am very knowledgeable about toxicology

mudplayerx 26 Feb 2014

I work in a hospital lab as a MLS (medical laboratory scientist). You have to understand the testing before you can ask or answer this question.

First of all, there is qualitative (screen) tests and quantitative tests that not only give a positive or negative result, but an amount detected. The quantitative tests are the only ones usuable for legal cases such as court cases, probation, or pain clinic compliance.

The qualitative tests are mainly used in hospital ERs and in pre-employment drug screens. They are highly sensitive but not very specific, so false positives are common. They come in different kits that tests for different drugs. You may get lucky and not get tested for the drug you are abusing.


On the other end of the spectrum, quantitative testing basically tests for all drugs that can be abused, legal and illegal. First is a quantitative screen done on a clinical hospital style instrument via immunoassay. These tests are pretty sensitive and very specific. Once this tests positive, the lab will extract the drug and its metabolites from your urine via chemical means.

After the drug is extracted it will be analyzed via another means, usually gas chromatography. This method is close to infallible and will find even minute traces of the drug. Some labs even used a third testing method in the middlw of this process.

Long story short, if you are getting drug tested for a legal reason like court or pain clinic complaince good luck getting away with absusing drugs and passing your test unless you wait the correct amount of time for it to pass completely from your system.

Aldulturating your urine won't work either becuase they also test urine pH, specific gravity, creatinine, and other things affected by adulturation.

Votes: +1
Mike Curtis 13 Dec 2014

What does anything you posted have to do with Flexeril. You of all people should know that muscle relaxers are not tested for on 10 panel or any other panel drug screen. Nor would it should if/when sent off to GC/MS.

miamivirgo918 28 Aug 2013

I just took a probation drug test and I had took 2 flexeril last night and today before before the test. It DID NOT show up ;-)

Votes: +0
christineATU 19 July 2010

Both answers are correct. But also remember, there are spaces on the Ameritox form (one of several testing labs) where the tester can write in any medication the person paying for the test wants you tested for. There are also boxes they can check off (suboxone is one of them) if they want you tested for it. It all depends on how much money the test requester wants to pay and if they think you may be taking something other than the standard drugs they normally test for. Bottom line... most people do not want to pay for the more in depth testing. So I wouldn't worry at all.

Votes: +4
christineATU 19 July 2010

I know mrspage is tired of reading this but I thought you might find this interesting...

"Statistical Information About Drug Testing and Passing Drug Tests"
Provided by HealthTech Inc.

According to R. Brookler, "Industry Standards in Workplace Drug Testing," Personnel Journal, (April 1992). Laboratories admit that urine tests are not always accurate. The manufacturers of all drug testing equipment acknowledge that all positive results should be confirmed with a more sophisticated test. The only acceptable drug confirmation test is the costly gas chromatography/mass spectrometer. Without confirmation by an alternative testing method, urine drug tests are not sufficiently reliable to hold up in court.


"Only 85 of the estimated 1,200 laboratories in the United States currently testing urine for drugs meet federal standards for accuracy, qualified lab personnel, and proper documentation and record-keeping procedures. Because private companies are not required to use certified drug testing labs, workers are being asked to put their job security in the hands of a drug test that has insufficient quality controls."

Even in labs that do meet the minimum standards, there is plenty of room for error. Your urine sample will change hands many times before its actual drug analysis, which increases the risk of mix-ups and errors. Also, the chemical reagents used in drug testing have a limited shelf life, which can cause "false positives". (A false positive is a sample showing a positive for drug metabolites when there are no metabolites in the person's system.)

Most states do not regulate the operations of urine drug test labs; in fact, some labs have fewer quality control regulations than restaurants. Your typical private employer may use any lab she/he chooses, which would most likely be the least expensive. Findings from the Center for Disease Control in Atlanta stated: "... the labs somehow detected cocaine in as many as 6 percent, and amphetamines in up to 37 percent of urine specimens that were 'blank" (those containing no drugs at all)."

Inactive 19 July 2010

Yes i remember chris where were you when i needed you i cant remember all of that by memory lady.

toxmd 16 July 2010

MD toxicologist to the rescue.
Answer: NO
Flexeril will not show up on a urine toxicology screen.
If this answer is helpful, please indicate such.
God bless

Votes: +7
joeblue 6 Jan 2012

Excuse me Dr. I must disagree, Flexeril will show up as a tricyclic antidepressant. As many drug test now a days test for. You yourself should know this as being a toxicoligist MD, Flexeril branches off the tricyclic antidepressant family. I don't mean to be disrespectful or anything.

emmarosewrites 24 Aug 2012

Doc this is not to you, but to the person who insists that they will show up on a drug test.
I'm confused, why would an employer care about tricyclic antidepressants? If a screen showed up for any antidepressant, I'm sure that would not prohibit someone from obtaining employment. I think someone is missing the point here.

Plus, most employers don't do that sort of test. If they are testing specifically for antidepressants, then one could show up, but the typical pre-employment drug screen tests for the following: Cocaine, Marijuana, Opiates, Methamphetamines, Benzodiazepines with the possibility of testing for Phencyclidine, Oxy, or Meth specifically.

J4go 18 April 2014

Once again john Blue is Dead wrong flexeril is a member of the cns muscle relaxant family not tricyllic anti-depressant family. Don't give bogus medical advice on the internet if you don't know what you are talkin about.

samantha092312 16 Aug 2014

I am on intensive supervision probation and I am on a daily ua hotline. I need to know if flexeril will show up on my ua when I have to take one. They have me on robaxin but it is more expensive than flexeril and will work the same probably better & it is cheaper.

Forensic P 4 Nov 2014

Excuse me Mr. Joe blue but I’m sorry to burst the little bubble you thought you had but I am a Forensic Pathologist and just in case you do not know what that is its a person that performs autopsies and in ten years of performing autopsies I have to perform toxic screenings and your common and uncommon muscle relaxers does NOT reveal in a toxic screening machine. And if you do not believe me I would advise you to go to college for 15 years as I have.

Yummybear1 31 Jan 2017

I am not an employer, but I process UAs for residents and do check for any meds prescribed to be sure residents are taking their meds. Just my thought.

Crafty07 27 Aug 2017

I know this is an old question I can't tell who is right. My husband drinks those energy drinks on a daily basis specifically monster and venom and he tested positive for TAC kind of makes you wonder what's in those drinks. And he wasn't taking anything else. Maybe Flex will not show up however you have to think of what you consume daily that can throw false positives.

Koljohnson07 29 June 2018

I'm a toxicologist who worked to validate many of these tests. Please see my response. It will show up, it isn't a TCA, but it will give a false positive screen for TCAs with a negative confirmation once sent to the lab, TCAs are routinely checked now for work place drugs because the POC cups come with it on the drug panel on the cup.

I know this is an old question, but it is one I see many times. I work in toxicology testing, performing data analysis for drug tests both in the work place and for pain management. I just wanted to reply so that other people may find the answer.


Short answer: yes it can show up, no it is not on a typical UA panel for confirmation but it cross reacts with a screen on the pee cup, it is not a TCA, but it does give a false positive for the TCA screen on the POC cups. TCAs are commonly checked on those cups now, if this happens to you, it will be sent for confirmation for the TCA panel and come back negative since Cyclobenzaprine (Flexeril) is not actually a TCA.

Long answer for those curious:
Cyclobenzaprine (Flexeril) can show up on drug tests. While previously TCAs were not routinely screened for for work place drug testing, I have seen many point of care testing cups have this screen on them (just took one today for a job with it on it). Cyclobenzaprine is not a TCA. That is true, however, with point of care testing cups and all screening sources for that matter, it will yield a false positive. Your sample will then need to be sent out for confirmation. In order to proclaim you as nok compliant or violating the terms of your employment, you need both a positive screen and positive confirmation. Since Cyclobenzaprine is not actually a TCA, once your sample is tested for confirmation, it will come back negative for the TCA panel. Some panels can tests for cyclobenzaprine in confirmation, however this is not routinely done and would be a separate test requested outside of the TCA confirmation panel. I have only rarely seen this done and never in the work place situation. Usually only for doctors wanting to check that their patient is taking it to confirm if it's not working or they're not taking it or if they see the point of care cup as positive for the screen and keep getting negatives on the confirmation they may request it to be certain the interference is due to this drug.

I know this to be true because today my POC cup flagged barely positive for TCAs. I have never been on TCAs but do have a script for cyclobenzaprine and took one 2 to 3 days ago. The first time I did not produce enough to send out so I had to wait, drink water, and take another one. The second time because it had been about 3 days since I last took one and the sample was so dilute it came back negative and it was all kind of a waste of my time for something I knew was a false positive to begin with but hey they have to check. I got a copy of the panels they test for on my discharge sheet and was able to confirm this was the only non illegal drug being tested for in the POC cup. I was also asked after the first sample if I took medication because they were waivering on whether or not to call it positive or negative since it was so faint. I told them I did and thus had to redo it. Anyways, just wanted to throw in my experience as well as my knowledge because some people say "yeah, it's a TCA" other's correct them and say "no it's not" and then others will say "they don't even test for it". The truth as you can see lies somewhere in the middle and thus why there's so much confusion. Hope this helps anyone in search of answers! It's always good to know what's happening to your bodily fluids and how they are being handled regardless of whether or not "you're guilty". It's your sample and you're right to be educated on the process.

Ottomitchell93NP 24 Oct 2020

I realize that this is 10 years old. And I also realize that there is probably a ton of responses that explain to this to the person that thinks Flexeril is a tricyclic antidepressant. First of all it is not a tricyclic antidepressant. I actually would have to look up whether it has any antidepressant effects whatsoever. But even if it was a tricyclic antidepressant, then a standard urinalysis or even one that gets sent out to a lab, like the ones I take that test for 24 substances, or rather their metabolites, it will not be detected. There is no reason to test for tricyclic antidepressants in the first place. Not only are tricyclic antidepressants totally void of euphoria or addictive properties but high doses of them actually can make you feel quite awful. I could go on not about antidepressants, muscle relaxers, addiction, toxicology, urinalysis, and everything in between but I realize that this post is 10 years old so I'm going to stop here. Hopefully if someone visits this page then my post will help.

Inactive 16 July 2010

Flexaril is simply a muscle relaxent just like many people think soma is a narcotic because it has the potencial for addiction. NO it will not show up as anything on a UA(tox screen). Hope this was helpful have a good day!

Votes: +3
joeblue 6 Jan 2012

You are wrong sir as i have said to the doc, flexeril is a member of the tricyclic antidepressant family,and many test panel and lab test for this on a reg. Sorry to burst your bubble

J4go 18 April 2014

JohnBlue is dead wron it does not belong to the tricyllic or any other anti-depressant family.

J4go 18 April 2014

My bad JoeBlue

J4go 18 April 2014

Joe Blue has no idea what he's talking about Flexeril is a member of the CNS muscle relaxant family not tricyllic antidepressants

gizmogrrl 9 Aug 2014

My apologies but he is not "dead wrong". Perhaps, in the future you should humble yourself just slightly enough to research things, before immediately objecting to the legitimate comments of others.

Mike Curtis 13 Dec 2014

Correct. Flexeril is not tested for on a 10 panel or any other panel drug screen.

Mike Curtis 13 Dec 2014

JoeBlue and Gizmogirl, perhaps you should go to school and educate yourselves. Humble yourself, you are dead WRONG.

Samsgun357 31 Dec 2014

It absolutely dies show up in a DT and it shows as a TAC as joeblue said. I took a DT today and was told I failed for THC but she looked at it wrong, it was a Tricyclic antidepressant from my flexeril script.

straighthoney 27 Jan 2017

It showed up on my drug screen on a Tuesday and the last one I took was on the Saturday before.
Don't risk it if you do not have a current script.

Yummybear1 31 Jan 2017

Unfortunately, your statement that it will NOT show up is incorrect. As an AODA therapist who customizes UAs, I can with great confidence assure you that it can be tested for. On an instant kit, 10 panel, it may not show. However, some labs can and do test for almost any drug out there.

shawnvest1 13 Sep 2017

You are both right and wrong, Flexeril is a CLOSE RELATIVE to tricyclic antidepressants, it will show, but can show as Elavil, Nortriptyline, Paxil, and others. It will show as Cyclobenzaprine on a mass spec, which some labs do regularly as some do not.

KatBrianna 9 Jan 2018

Thank you. I do have a prescription for it, but when one is doing a UA for a job I've been told that being on Flexaril could make it harder to obtain a job. Friends told me to just not say anything. That is the reason for my question.

WickedWeSToN83 17 Oct 2018

Well to settle the debate, I just took a 10 panel drug test and I'm prescribed Flexeril, and it didn't show up. And the methylphenidate(Ritalin) did not as well. Very interesting. I believe both of you are right in a way... free discount card

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