Last updated : December 23, 2024
The Department of Transportation (DOT) mandates drug testing of the safety-sensitive workforce to keep people traveling throughout the country as safe as possible. There’s no doubt that the DOT drug test is worthwhile. The Federal Motor Carrier Safety Administration (FMCSA) Drug and Alcohol Clearinghouse (DACH) reported that since the database went live in January 2020, over 227,000 commercial motor vehicle drivers have failed a drug test and were removed from service.
Drug testing technology has become very advanced over the years and the sensitivity of laboratory equipment even more precise. It’s nearly impossible for a drug test result to show an inaccurate result. That information doesn’t stop the occasional driver who tested positive for drugs from disputing the results of their DOT drug test though.
What happens then?
When informed of the positive test result, the employee can dispute it for 72 hours. If disputed, a second, more in-depth, test is performed on the specimen.
Split specimen test
The DOT’s drug testing protocol stipulates that the urine specimen be divided into two separate collection cups.
Initially, testing is completed on one of the specimens. The second is stored for 72 hours. If for any reason during that time, the employee notifies the Medical Review Officer (MRO), either verbally or in writing, that they don’t agree with the test result, the second specimen is sent to a different SAMHSA-certified laboratory for further testing.
It’s important to note that the split specimen test will not be performed if the first test proves invalid.
Should the “backup” specimen be returned with a positive result, the MRO contacts the employee. It could be that there is a valid reason for the positive test result. Some medications are known to cause a false positive drug test result. If the employee can present evidence that they have been taking prescription medications or over-the-counter medications that are known to cause positive test results, the MRO will confirm the same to the employers and anyone else required to know the information.
We should note here that the DOT recently released a final ruling regarding oral fluid tests. They are allowed as an alternative to the urine drug test. Protocol mandates a split sample test be administered using the mouth swabs as well. Employers can’t begin using the test yet, though, because to date no laboratories have been approved by SAMHSA to perform testing.
Drugs that trigger false positive results
It’s possible that the DOT drug test result could be inaccurate due to a laboratory error. However, those occurrences are extremely rare. It’s more likely that another form of medication has triggered a false positive result on the urine test.
Some medications that are known to affect DOT drug testing are:
- Dextromethorphan—found in Robitussin and Delsym—can trigger a PCP result
- Diphenhydramine—found in Benadryl—can trigger an opioid result
- Pseudoephedrine—found in certain decongestants—can trigger and amphetamine or methamphetamine result
- Phentermine—a weight loss medication—can trigger an amphetamine result
- Quetiapine—used to treat certain mental health conditions—can trigger an opioid result
- Proton Pump Inhibitors—used to treat gastroesophageal reflux disease (GERD) and heartburn—can trigger a THC result
- Promethazine—used to relieve nausea and vomiting—can trigger both amphetamine and methamphetamine results
- NSAID’s—Ibuprofen, and naproxen, both used to treat fever, inflammation, and pain—can trigger both THC and barbiturate results
- Quinolone Antibiotics—used to treat bacterial infections—can trigger either amphetamine, methamphetamine, or opioid results
- Venlafaxine and Desvenlafaxine—antidepressant medications, such as Effexor XR and Pristiq—can trigger a PCP result
- Sertraline—brand name Zoloft—can trigger both Benzodiazepine and LSD results
- Trazodone—an older antidepressant that’s not used often—can trigger amphetamine and methamphetamine results
- Bupropion—brand name Wellbutrin—can trigger amphetamine and methamphetamine results
Proof positive
If someone disputes the result of a DOT drug test, the odds are that one of the medications listed above is in their system. False positive results on urine drug tests are unlikely, but possible, even though the person never ingested the drug—ever!
The MRO is capable of determining if that’s the case and alerting all necessary parties—such as the employer and the FCMSA Drug and Alcohol Clearing House to record the false positive result.
