Will flexeril (cyclobenzaprine hcl) give you a false positive on a drug test? i have recently been prescribed flexeril (cyclobenzaprine hcl) and took a drug test and i failed it. i do not do drugs and it showed up as thc why is this

Through : Through my research on this question, it appears that Flexeril (cyclobenzaprine hcl) will not cause a positive thc result. One common medication that causes a false positive thc is ibuprofen. This is found in advil, motrin, and nuprin. So if you have recently taken any of these that may be the problem. I also recommend that you ask for a copy of the test. Make sure the name, id number, and any other iddentifying information matches up. Good luck.

Not likely: Most drug tests use a first test, TLC or thin layer chromatography, as an initial screen. This test is prone to cross-reaction or "false positive" results for some substances. Usually if the TLC is positive, a second test, gcms or gas chromatography mass spectroscopy is used to confirm. This test is much more specific for specific molecules and not likely to yield false positive results.