Can Cyclobenzaprine (Flexeril) show up on a drug test? 

Can Cyclobenzaprine (Flexeril) show up on a drug test? 

No, Cyclobenzaprine (Flexeril) does not show up on the standard drug urine immunoassay. However, it will show up if the test is specifically done to check the presence of Cyclobenzaprine. 

This medication is a muscle relaxant and is not recommended to be used for more than 10 days. Now, Cyclobenzaprine is not a substance of abuse and will not show up on a general drug testing procedure. 

The medication is also not known to cause a false positive or make you fail a drug test. However, if you’re being checked for Cyclobenzaprine, it will definitely show up. 

How long does Cyclobenzaprine stay in your system? 

Cyclobenzaprine has a long half-life and it stays in your system for about 18-24 hours, but it can go as high as 37 hours in some people (1). 

Because of the longer half-life, Cyclobenzaprine can take 4 to 8 days to leave your system completely and it is detectable in urine tests during this time period. 

If you’re on standard doses, the drug will definitely not show up and if you’re taking a prescription medication, you don’t need to worry about it. 

However, if you’re overusing the medication – it will still not show up on a drug test, but there is no way to be certain. Make sure you only take as much Cyclobenzaprine as prescribed by your healthcare provider. 

Cyclobenzaprine and other muscle relaxants like Methocarbamol can be used for muscle pain, but these medications can not help with other kinds of pain, like dental pains. So, make sure you are using the medication for the right reasons.

How to generally prevent getting a false positive?

There are a number of medications which are known to cause false positives. The easy fix is to avoid using the culprit medication 2-3 days before the test to give your body enough time to get rid of the medication. However, not every single medication can be skipped. 

There are some meds like antidepressants and antipsychotic medications that can cause a false positive but you should never stop taking these meds for the sake of avoiding a false positive. 

The best way to deal with that is to talk to your healthcare provider and inform the drug testing authorities about your prescription medication that can cause a false positive. This way, getting a false positive will not affect you in any way.

However, if your testing technique is more accurate than the preliminary urine drug immunoassay, you may not get any false positives because of the accuracy of the tests.

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PubChem [Internet]. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information; 2004-. PubChem Compound Summary for CID 2895, Cyclobenzaprine; [cited 2023 Jan. 8]. Available from: