When performed properly, the accuracy of most mouth swab tests is close to 98 percent. However, there are a few things that can affect accuracy, including: the type of test used. the drug type and concentration.

Still, if you want the most accurate option available, a blood test is the way to go.

Several common medications can lead to a false positive on a drug screen, including but not limited to: brompheniramine, bupropion, chlorpromazine, clomipramine, dextromethorphan, diphenhydramine, doxylamine, ibuprofen, naproxen, promethazine, quetiapine, quinolones (ofloxacin and gatifloxacin), ranitidine, sertraline, ...

A false positive is when a drug test shows the presence of a medication or substance that hasn't actually been taken. Multiple medications can cause false-positive drug tests. Some examples include ibuprofen (Advil, Motrin), dextromethorphan (Robitussin), and certain antidepressants, including sertraline (Zoloft).