How Fentanyl Drug Tests Work & How to Interpret the Results in 3 Steps

Drug tests. Sometimes the only thing standing between our suspicions and confirmations. If you’ve ever been in a situation where you felt someone you loved was using fentanyl, yet they vehemently denied such actions, you’ve probably had to rely on a drug test. Pretty straightforward to use. A bit more different to interpret. As the rates of fentanyl use continue to rise, fentanyl drug tests are becoming of greater importance to saving lives. Keep reading to learn how these tests work and how to confirm the results. 


Understanding Fentanyl Drug Tests


Testing for fentanyl can be done in a variety of ways. Here are the different ways fentanyl can be tested for and how each test works:

Urine Tests: The most common method for testing fentanyl use, the medical professional collects a urine sample and tests it. When fentanyl is ingested, it is metabolized by the body into different metabolites such as norfentanyl and despropionylfentanyl. Urine tests detect the presence of these metabolites and can indicate fentanyl use. 

Blood Tests: While blood tests are more invasive and less popular, they generally provide the most accurate and immediate results. Typically used in ER situations, a blood sample is taken from the individual and tested for fentanyl metabolites in the body. 

Saliva Tests: It is possible to detect fentanyl from a saliva sample. The downside to saliva tests is that they can only detect fentanyl use within the last 24 hours. 

Hair Tests: While not commonly used, hair tests generally allow for testing over a longer period of time. Fentanyl hair testing can detect the presence of fentanyl metabolites up to 90 days from last use.


Interpreting Fentanyl Test Results


Here is our three-step guide to interpreting fentanyl test results:

  1. Review the Threshold: All drug test results will fall into a threshold concentration. This threshold is what differentiates a negative test from a positive test. Fentanyl tests also have a threshold concentration depending on the type of test used. Find the specific threshold for the fentanyl test being used. If the test results are below that threshold, the test is negative. If the results are above the threshold, the results are positive. 

  2. Consider the Context: When interpreting a fentanyl test result, it’s crucial to know the context in which the drug test is administered. Different agencies will have different guidelines on testing and how it is to be done. Medical professionals, employers, and law enforcement agencies all require fentanyl testing to be done in a specific way. It’s important that the testing environment and protocols meet the policies desired in order to get a workable test result. 

  3. Verify with Confirmatory Testing: False positives/negatives are a possibility with all drug tests including fentanyl drug tests. Using gas chromatography-mass spectrometry (GC-MS) as confirmatory tests can provide more accurate results. It’s best practice to not use the entire sample on the first test, in the event that you need to test it again. It’s advised that positive fentanyl test results be followed up with confirmatory testing to make sure there weren’t any errors. 


Drug tests for fentanyl are a vital part of detecting drug use and encouraging people using fentanyl to get help. With a working knowledge of specific testing methods, when to use them, and how to interpret the results, you’re better equipped to help the community. Consult with professionals when necessary. 

If you or someone you love is struggling with fentanyl use, call Sunflower Recovery today to learn more about our detox and treatment options. You can get off fentanyl. We can help. 

Fentanyl Drug Testing 101