This article was published on July 21, 2022. It was last edited on August 28, 2022.
Given the seriousness of the fentanyl epidemic and the huge number of people who are dying each year due to it, all articles on this website about fentanyl and fentanyl analogs are being made available to everyone and not only to our Members (subscribers). Please share these articles widely by email, social media, and other means.
Here are the links to the articles about fentanyl and fentanyl analogs:
In another article on this website, we noted how serious the problem of fentanyl misuse has become. And that it is common for users of illicit substances to not know that fentanyl or a fentanyl analog has been added to the substance they are using.
For these reasons, it is very important for us to expand the substances we are screening our patients for to include fentanyl.
Standard urine drug screens will not detect fentanyl
Given the skyrocketing use of fentanyl—intentional or unintentional—in the United States, It is important for us to realize that standard urine drug screens will not detect fentanyl.
An example of what I am calling a “standard” urine drug screen is the “Drug Abuse Profile, urine (9 drugs)” offered by Labcorp® (a large chain of laboratories in the US).
Why not? Because fentanyl is a synthetic product and not a natural opioid derivative. Just like oxycodone and methadone, it is not metabolized to morphine (Shelton, 2022). These opioids have to be specifically tested for separately. Which urine drug screen panel should we ask for then?
Option 1: Test just for fentanyl
Of course, we could simply order a urine test just for fentanyl.
For example, Labcorp® offers a “urine screen and confirmation for fentanyl/ norfentanyl” for which their test number is 764200 and which we can see on their website at this LINK.
Similarly, Quest Diagnostics offers a test called “Drug Monitoring, Fentanyl, with Confirmation, Urine”. Their test code for this test is 39375 and we can see it on their website at this LINK.
Option 2: Broader test that also includes fentanyl
But, when misuse of opioids, including fentanyl is suspected, it may make more sense to order an expanded urine drug screen panel rather than a basic urine drug screen plus a test specifically for fentanyl.
One author persuaded his hospital to change the urine drug screen panel they were using in their emergency room to one that also tested for fentanyl, and the cost difference was only $2.50 (Shelton, 2022).
As an example of a broader-than-usual urine drug screen, Labcorp® offers a 14-drug urine drug screen (LINK). Their test code for this test is 764442. Opioids that would be missed by the more commonly used urine drug screen panels are specifically tested for in this panel. These include:
– Fentanyl/ norfentanyl
Option 3: Add an expanded opioid panel
If a basic urine drug screen has already been done and an expanded screening for other opioids, including fentanyl, is needed, we can order an expanded opioid panel.
For example, Quest Diagnostics (another large chain of laboratories in the US) offers a test called “Drug Monitoring, Opioids Panel, with Confirmation, urine”. Their test code for this panel is 39013 and we can see it on their website at this LINK.
What would cause a false positive for fentanyl on a urine drug screen?
Question from a Member:
My patient [was positive for] fentanyl on three separate occasions. However, the patient is negative for the fentanyl metabolite, norfentanyl. The test was negative for opiates. This patient is on Suboxone® 8/2 (buprenorphine 8 mg plus naloxone 2 mg), topiramate, buspirone, doxepin, and risperidone. What would cause a false positive for fentanyl on a urine drug screen?
We should be aware that due to structural similarities, some medications can lead to a false-positive result for fentanyl on immunoassay urine drug screens. These false-positive results on the initial urine drug screen by immunoassay—before confirmatory testing by mass spectrometry is done—are not rare (Kerensky et al., 2021). So, it is important for us to wait for confirmatory test results before concluding that the urine is positive for fentanyl.
The medications that have been reported to be associated with false positives for fentanyl include (Kerensky et al., 2021):
Risperidone (Three cases reported by Shroitman et al., 2021; five cases reported by Wang et al., 2014).
Ziprasidone (case report by Waters and Tewksbury, 2022).
Labetalol (Three cases reported by Wanar et al., 2022).
Other illicit substances
Methamphetamine (Abbott et al., 2022; Lockwood et al., 2021)
MDMA (Lockwood et al., 2021)
Diphenhydramine (used commonly to “cut” heroin; Lockwood et al., 2021)
So, in our Member’s case, the risperidone could be the cause of the false-positive fentanyl. The list above is very relevant because it shows that several psychiatric medications can cause false-positive tests for fentanyl.
If the patient denies using any illicit substances and is on one or more psychiatric medications, before we overreact, we should wait for the confirmatory test to come back.
Simple and Practical Medical Education thanks (alphabetically) Jonathan Beatty MD, and Marina Goldman, MD, for peer-reviewing and approving this article (in July and August 2022).
Dr. Beatty is a board-certified addiction psychiatrist in Philadelphia, Pennsylvania, who has extensive clinical experience in treating patients with substance use disorders. His clinical practice website is https://wavetreatmentcenters.com.
Dr. Goldman is a board-certified addiction psychiatrist. She is a Clinical Assistant Professor and Core Faculty in the Addiction Medicine & Addiction Psychiatry Fellowships at Thomas Jefferson University, Philadelphia, Pennsylvania. She also has a busy private practice in Jenkintown, Pennsylvania.
Urine drug screens
Abbott DL, Limoges JF, Virkler KJ, Tracy SJ, Sarris GG. ELISA Screens for Fentanyl in Urine Are Susceptible to False-Positives in High Concentration Methamphetamine Samples. J Anal Toxicol. 2022 Apr 21;46(4):457-459. doi: 10.1093/jat/bkab033. PMID: 33835171.
Kerensky T, LaRochelle M, Fan SL, Kosakowski S, Wason K, Walley AY. Non-prescription Fentanyl Positive Toxicology: Prevalence, Positive Predictive Value of Fentanyl Immunoassay Screening, and Description of Co-substance Use. J Addict Med. 2021 Apr 1;15(2):150-154. doi: 10.1097/ADM.0000000000000723. PMID: 32909981.
Lockwood TE, Vervoordt A, Lieberman M. High concentrations of illicit stimulants and cutting agents cause false positives on fentanyl test strips. Harm Reduct J. 2021 Mar 9;18(1):30. doi: 10.1186/s12954-021-00478-4. PMID: 33750405; PMCID: PMC7941948.
Shelton D. Fentanyl not detected in routine urine drug screens: case report. CJEM. 2022 Apr;24(3):335-336. doi: 10.1007/s43678-022-00274-4. Epub 2022 Feb 9. PMID: 35138594.
Shroitman NK, Peles E, Even-Tov S, Schreiber S, Tene O. False-positive fentanyl screening kit results during treatment with long term injectable risperidone (Risperdal-Consta). Psychiatry Res. 2021 Nov;305:114246. doi: 10.1016/j.psychres.2021.114246. Epub 2021 Oct 19. PMID: 34717208.
Wanar A, Isley BC, Saia K, Field TA. False-positive Fentanyl Urine Detection After Initiation of Labetalol Treatment for Hypertension in Pregnancy: A Case Report. J Addict Med. 2022 Aug 16. doi: 10.1097/ADM.0000000000001010. Epub ahead of print. PMID: 35972891.
Wang BT, Colby JM, Wu AH, Lynch KL. Cross-reactivity of acetylfentanyl and risperidone with a fentanyl immunoassay. J Anal Toxicol. 2014 Nov-Dec;38(9):672-5. doi: 10.1093/jat/bku103. Epub 2014 Sep 23. PMID: 25248490.
Waters K, Tewksbury A. A false positive fentanyl result on urine drug screen in a patient treated with ziprasidone. J Am Pharm Assoc (2003). 2022 May 17:S1544-3191(22)00149-2. doi: 10.1016/j.japh.2022.05.011. Epub ahead of print. PMID: 35672206.
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