A DOT drug test screens for five categories of drugs: marijuana, cocaine, opioids, amphetamines, and phencyclidine (PCP). This standardized five-panel urine test applies to roughly 6.5 million workers in safety-sensitive transportation roles across the United States, and the specific substances within each category are broader than many people realize.
The Five Drug Categories
The Department of Transportation mandates testing through HHS-certified laboratories under 49 CFR Part 40. The five panels break down as follows:
- Marijuana (THC): The test detects THC, the psychoactive compound in marijuana. This includes all sources of THC, not just smoked cannabis.
- Cocaine: Both cocaine and its metabolites are screened.
- Opioids: This category covers traditional opiates like codeine and opium derivatives, plus four semi-synthetic opioids: hydrocodone, oxycodone, hydromorphone, and oxymorphone. Those four were added to the panel in a rule update, expanding coverage beyond older drugs like heroin and morphine.
- Amphetamines: The panel tests for amphetamine, methamphetamine, MDMA (ecstasy), and MDA.
- Phencyclidine (PCP): Also known as angel dust.
If you have a valid prescription for a medication that falls within one of these categories, such as hydrocodone or amphetamine-based ADHD medication, a Medical Review Officer (MRO) will contact you after a positive result to verify your prescription before finalizing the test outcome.
What It Does Not Test For
The DOT panel does not screen for alcohol (that’s handled through separate breath or saliva testing), benzodiazepines, barbiturates, synthetic cannabinoids like K2 or Spice, kratom, or other substances commonly found on broader 10- or 12-panel workplace tests. The test is strictly limited to those five categories. Your employer cannot add extra panels to a DOT-required test.
CBD Products and Marijuana Policy
The DOT tests for marijuana, not CBD specifically. But this distinction is less reassuring than it sounds. CBD products can contain higher THC levels than their labels claim, and the FDA does not certify THC levels in CBD products. There is no federal oversight ensuring label accuracy.
If you use a CBD product and it triggers a positive result for THC, the Medical Review Officer will not accept CBD use as a legitimate medical explanation. The result stands as a verified positive. The DOT’s position is clear: marijuana remains a Schedule I substance under federal law, and no safety-sensitive employee subject to DOT testing may use it, regardless of state legalization. The same applies to delta-8 THC and other hemp-derived cannabinoids that could produce a positive THC result.
How the Testing Works
DOT drug tests are currently conducted using urine specimens collected under strict chain-of-custody procedures. The lab runs an initial immunoassay screen, and any sample that crosses the cutoff threshold goes through a second, more precise confirmation test. For amphetamines and MDMA, the initial screening cutoff is 500 nanograms per milliliter (ng/mL), dropping to 250 ng/mL for confirmation. Each drug category has its own pair of cutoff levels, and a result is only reported as positive after passing both rounds of testing.
The DOT authorized oral fluid (saliva) testing as an alternative to urine in June 2023, but as of January 2025, no HHS-certified oral fluid laboratories with DOT-conforming devices exist. Until at least two such labs are certified, all DOT testing remains urine-based. The DOT plans to announce in the Federal Register when oral fluid testing becomes available.
Who Has to Take This Test
DOT drug testing applies to employees performing safety-sensitive functions regulated by six agencies: the Federal Aviation Administration (aviation), the Federal Motor Carrier Safety Administration (trucking), the Federal Railroad Administration (rail), the Federal Transit Administration (mass transit), the Pipeline and Hazardous Materials Safety Administration (pipelines), and the United States Coast Guard (maritime). If you’re a commercial truck driver, airline pilot, train engineer, bus operator, pipeline worker, or merchant mariner, you fall under these rules.
Testing can happen at several points: pre-employment, random selection during employment, after an accident, when a supervisor has reasonable suspicion, and as part of a return-to-duty process.
What Happens After a Positive Result
A confirmed positive DOT drug test triggers immediate removal from safety-sensitive duties. You cannot simply retest or wait it out. The process for getting back to work follows a structured path through a Substance Abuse Professional, known as a SAP.
Your employer provides you with a list of DOT-qualified SAPs. You choose one, and they conduct an initial evaluation to assess the situation and recommend education or treatment. After you complete whatever program the SAP prescribes, they re-evaluate you to confirm compliance and set up a follow-up testing plan. Only then can your employer send you for a return-to-duty test. A negative result on that test is required before you can resume safety-sensitive work, and you’ll face additional unannounced follow-up tests for a period determined by the SAP.
For commercial drivers specifically, positive results and the return-to-duty process are recorded in the FMCSA Drug and Alcohol Clearinghouse, a national database that other employers can query when hiring. A violation stays in the Clearinghouse until the full return-to-duty process is complete and documented.