What Drugs Are Tested for on a DOT Drug Test?

A DOT drug test checks a single urine specimen for five drug classes: marijuana (THC), cocaine, amphetamines (including MDMA and MDA), opioids (codeine, morphine, heroin, hydrocodone, hydromorphone, oxycodone, and oxymorphone), and phencyclidine (PCP). This is the federal 5-panel required under 49 CFR Part 40 for every safety-sensitive employee in the DOT-regulated trucking, transit, aviation, rail, and pipeline industries. It does not screen for alcohol on the same specimen, alcohol testing is a separate procedure with its own breath or saliva device and its own cutoffs.

Every carrier subject to FMCSA rules has to run this panel for pre-employment, random, post-accident, reasonable suspicion, return-to-duty, and follow-up testing. If you are a driver wondering what is actually being checked, or a carrier trying to make sure your program is built correctly, here is the full breakdown: the drug classes, the cutoff levels, how the specimen is collected and verified, what triggers a positive versus a refusal, and what happens after either one.

The DOT 5-panel: what is actually tested

The DOT drug testing panel is defined in the Department of Transportation's Part 40 procedures and mirrors the drug classes used across all six DOT operating administrations. It is not a broad toxicology screen, it targets five specific drug classes, and nothing outside those classes shows up on the official result.

Notice what is not on that list: no fentanyl, no benzodiazepines (Xanax, Valium), no barbiturates, no synthetic cannabinoids (K2/spice), and no alcohol. A driver can fail a state or employer-specific test for one of those substances, but it would not be a DOT-regulated positive unless the carrier separately requires it under a company policy that runs outside the federal program. Some carriers do add non-DOT panels for insurance or internal reasons, always know whether you are being tested under Part 40 or under a company add-on, because the consequences are very different.

The 2018 expansion to semi-synthetic opioids

Before January 1, 2018, the opioid panel only looked for codeine, morphine, and heroin metabolites. Effective that date, DOT expanded the panel to add hydrocodone, hydromorphone, oxycodone, and oxymorphone, the semi-synthetic opioids behind most prescription painkiller abuse in the country. This closed a gap that had let drivers taking Vicodin, Percocet, OxyContin, and Dilaudid pass a DOT test even while impaired on a controlled substance. Every DOT test collected since that date runs under the expanded panel; there is no legacy 4-panel option left anywhere in the system.

Initial screening vs. confirmatory cutoff levels

Every specimen goes through a two-stage laboratory process. The initial screen is an immunoassay that flags specimens above a lower cutoff. Anything that screens positive is automatically retested using gas chromatography/mass spectrometry (or an equivalent confirmatory method) against a second, generally lower, confirmatory cutoff. A specimen has to clear both thresholds to be reported as a verified positive, screening positive alone is never enough.

These numbers are set in the Part 40 regulation itself and in HHS Mandatory Guidelines for Federal Workplace Drug Testing Programs, which DOT incorporates by reference. Labs cannot use their own thresholds; the cutoffs are fixed nationwide so results are consistent no matter which certified lab processes the specimen.

How the collection actually works

DOT drug tests use a urine specimen collected at a certified collection site following a strict chain-of-custody procedure designed to prevent tampering and protect the driver's rights at the same time.

1. The driver reports to the collection site with photo ID. The collector verifies identity and explains the process.
2. The driver is given a sealed collection container and goes to a private stall to provide the specimen unobserved, unless a specific direct-observation trigger applies.
3. The specimen must be at least 45 mL and between 90°F and 100°F within four minutes of collection, the collector checks the temperature strip on the cup.
4. The specimen is split into two bottles: Bottle A (the primary specimen) and Bottle B (the split specimen), both sealed in the driver's presence.
5. The driver and collector sign the Federal Drug Testing Custody and Control Form, and the driver certifies the specimen is their own.
6. Bottle A goes to the lab for initial and, if needed, confirmatory testing. Bottle B is retained, sealed, in case the driver requests a retest of a positive result.

If Bottle A comes back positive and verified, the driver has 72 hours to request that Bottle B be tested at a second certified lab. This is the driver's one shot at disputing a lab-confirmed positive, and it is tested independently, it is not a re-run of the same sample at the same lab.

Shy bladder and insufficient specimen

If a driver cannot produce 45 mL, they are given up to three hours and encouraged to drink fluids reasonably (no more than 40 ounces). If they still cannot produce enough urine, the collector documents it as an insufficient specimen and the driver is referred to a physician for a medical evaluation to determine whether there is a legitimate medical reason. Without a documented medical explanation, failure to produce an adequate specimen is treated as a refusal to test, which carries the same consequences as a verified positive.

Adulterated, substituted, and dilute results

Labs also test specimen validity, not just drug content. A specimen can come back with a result other than positive or negative:

• Adulterated, the specimen contains a substance not normally found in human urine, or contains a substance at a concentration that is not consistent with human urine (bleach, glutaraldehyde, or other cheating-kit additives). Treated as a refusal to test.
• Substituted, creatinine and specific gravity values are outside the physiologically possible range, meaning the specimen is not consistent with human urine at all. Also treated as a refusal to test.
• Dilute, the specimen is within human range but has abnormally low creatinine and specific gravity, usually from drinking excessive fluids. A negative-dilute result stands as a negative; a positive-dilute result stands as a positive. Depending on the specific readings, the employer may be required to conduct an immediate recollection under direct observation.

The MRO verification interview

No lab result becomes an official DOT drug test result until a Medical Review Officer, a licensed physician trained in Part 40 procedures, reviews it. If the lab reports a positive, adulterated, or substituted result, the MRO must contact the driver directly, in a confidential interview, before verifying anything.

During that interview the driver can present a legitimate medical explanation, including a current prescription from a physician who knows the driver is a DOT-regulated safety-sensitive employee. If the explanation is legitimate and the prescription is valid for that driver, the MRO verifies the result as negative. If there is no legitimate explanation, the MRO verifies it as positive, and that verified result is what gets reported to the employer and to the FMCSA Clearinghouse.

CBD is not a defense

CBD products are widely marketed as THC-free, but FDA testing has repeatedly found CBD oils, gummies, and vapes with detectable and sometimes mislabeled THC content. The DOT lab test does not care where the THC came from, it detects the THC metabolite regardless of source. FMCSA and the DOT have stated plainly that CBD use is not a legitimate medical explanation for a positive THC result. Drivers who use CBD products are taking on a real risk with no regulatory protection if it triggers a positive.

State-legal marijuana is never a defense

Marijuana is legal for recreational or medical use in a majority of states, but DOT drug testing is governed by federal law, and marijuana remains a Schedule I controlled substance under the Controlled Substances Act. FMCSA and DOT have been explicit and consistent: state legalization has no effect on DOT testing requirements, and a state medical marijuana card is not a legitimate medical explanation an MRO can accept. A verified positive for THC is a verified positive no matter what state law says about the underlying use.

Detection windows

How long a drug stays detectable in urine varies by substance, frequency of use, metabolism, and hydration, so these are general ranges, not guarantees for any individual.

These windows are why random testing works as a deterrent even though it only samples a fraction of the workforce each quarter, occasional users cannot reliably time their use around a testing calendar they cannot predict.

Alcohol testing runs on a separate track

Alcohol is not part of the urine drug panel. It is tested using an evidential breath testing device (or in some cases saliva), typically at the same time as post-accident, reasonable suspicion, or random alcohol selections, using its own concentration thresholds under Part 40.

Refusals count the same as a positive

DOT treats a refusal to test as functionally identical to a verified positive, and refusal is defined more broadly than most drivers expect. All of the following count as a refusal under Part 40:

• Failing to appear for a scheduled test within a reasonable time after being notified.
• Failing to remain at the testing site until the process is complete.
• Failing to provide a sufficient specimen without a documented medical explanation.
• Failing to permit a required direct observation collection.
• Failing or declining to take a required second test the employer or collector directs.
• Tampering with, adulterating, or substituting a specimen, or attempting to do so.
• A verified adulterated or substituted laboratory result.
• Admitting to the collector or MRO that you adulterated or substituted the specimen.

A driver who simply walks out of the collection site because they know they will fail has not avoided a positive result, they have created a refusal, which triggers the exact same removal-from-duty and Clearinghouse consequences.

What happens after a positive or a refusal

The consequences are the same whether the driver tests positive or refuses, and they are immediate and non-discretionary under the regulations.

1. The driver is removed from all safety-sensitive functions immediately, no more driving that shift, period.
2. The employer reports the violation to the FMCSA Drug and Alcohol Clearinghouse within the required timeframe. The violation stays visible to every future DOT-regulated employer who queries the driver.
3. The driver must be evaluated by a Substance Abuse Professional (SAP), a specially credentialed counselor who determines a course of education or treatment.
4. The driver completes the SAP's prescribed treatment or education program.
5. The SAP conducts a follow-up evaluation and, only if satisfied, clears the driver for a return-to-duty test, which must be a directly observed collection.
6. The driver must pass the return-to-duty test before performing any safety-sensitive function again.
7. The driver is then subject to a follow-up testing plan set by the SAP: a minimum of six unannounced tests over the first 12 months, and the SAP can extend follow-up testing for up to five years.

A driver cannot self-certify their way back to work and no employer can waive these steps. Until the Clearinghouse shows a completed return-to-duty process, the driver is prohibited from performing safety-sensitive duty for any DOT-regulated employer, not just the one where the violation occurred.

What this means for your compliance program

Knowing what is on the panel is only half the job. Carriers have to run the whole program correctly: a compliant random testing pool at the right annual percentages, pre-employment testing with a negative result and Clearinghouse query before a driver's first day, post-accident testing within the regulatory time windows, reasonable suspicion training for supervisors, and designated employer representative duties handled by someone who actually understands Part 40. An auditor reviewing your program during a new entrant audit or a compliance review will ask for records on all of it, not just test results.

Most small and mid-size carriers do not run this in-house, it requires a random pool, a certified collection network, an MRO, a DER, and current SAP referral relationships, all documented and audit-ready. Long Haul Compliance handles the full consortium enrollment, random selection, and Designated Employer Representative duties for carriers who do not want to build and staff that infrastructure themselves, so drivers get tested on schedule and the paperwork holds up when FMCSA comes asking for it.