Last updated: November 27, 2023
The Department of Transportation (DOT) mandates drug testing of the safety-sensitive workforce to keep the highways and byways of the country as safe as possible for traveling. There’s no doubt that employee drug testing combats drug abuse in the workplace. However, from time to time, a driver who tested positive disputes the result of the DOT drug test.
What happens then?
When informed of the positive test result, the employee has the right to dispute it for a period of 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 specimen cups.
Initially, testing is completed on one of the specimens. The second is stored for a period of 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 proved invalid.
Should the “backup” specimen also come back positive the MRO will contact the employee. Some medications are known to cause a false positive drug test result. If the employee can present evidence that they had 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 in regard to allowing the oral fluid drug test as an alternative to the urine drug test. Protocol mandates a split sample test be administered using the mouth swabs as well.
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
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 can happen even though the person did not ingest that 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 of the false positive result.