Drug Testing: DOT's New Proposal to Add Fentanyl to the List

DOT Proposes Adding Fentanyl to Drug Testing for Truck Drivers

DOT May Expand Drug Testing Rules

The U.S. Department of Transportation (DOT) has proposed a new rule that would expand its federal drug testing program. The change would add fentanyl and its metabolite, norfentanyl, to the list of substances tested. This would apply to all safety-sensitive transportation workers, including truck drivers.

The rule was published in the Federal Register on September 2, 2025. DOT said the update is needed to match the Department of Health and Human Services (HHS) Mandatory Guidelines. By law, DOT must follow HHS standards for workplace drug testing and laboratory procedures.

Why Fentanyl Would Be Added

Fentanyl is a synthetic opioid that is extremely powerful. It is up to 50 times stronger than heroin and 100 times stronger than morphine. Doctors prescribe it for severe pain, but most overdose cases involve fentanyl made illegally. It is often mixed with counterfeit pills or other drugs. Users may not know they are taking it, which makes it even more dangerous.

According to data gathered by the DOT, fentanyl has become the leading cause of overdose deaths in the United States. DOT also writes that between 2016 and 2021, deaths involving fentanyl rose by 279 percent. In 2023, nearly 70 percent of all overdose deaths involved fentanyl or other synthetic opioids. 

DOT explained that adding fentanyl to required drug testing is a safety measure. The agency said this change will help ensure that truck drivers and other transportation workers are not impaired while on the job.

Impact of Drug Testing Changes on Truck Drivers

If finalized, the rule would add fentanyl to all required drug testing programs for truck drivers. This includes pre-employment screenings, random testing, post-accident testing, reasonable suspicion testing, and return-to-duty testing.

Employers and third-party administrators in the trucking industry would have to update their programs. Medical review officers (MROs) would review results and confirm whether a positive test should stand.

For truck drivers, a verified positive test would have serious consequences. Drivers would be removed from safety-sensitive duties, required to see a substance abuse professional, and complete a return-to-duty process before resuming work.

Morphine Changes in Drug Testing

The proposal also includes changes to morphine testing. At present, a urine test showing 2,000 nanograms per milliliter (ng/mL) or more of morphine or codeine is considered positive. But eating poppy seed products can sometimes produce levels that high.

DOT wants to raise the morphine confirmation cutoff level to 4,000 ng/mL. Research shows that normal food consumption would not trigger a result this high. Only extreme amounts of raw poppy seeds would cause a reading above 4,000 ng/mL.

DOT also proposes removing the requirement for MROs to look for “clinical evidence” of illegal opioid use in certain morphine cases. The agency explained that the new cutoff level makes this step unnecessary.

Oral Fluid Drug Testing Updates

DOT has allowed oral fluid drug testing since 2023. This method is less invasive and harder to cheat compared to urine testing.

Under the new rule, DOT would make oral fluid testing rules clearer. If codeine or morphine results fall between 15 ng/mL and 150 ng/mL, and a driver claims the result is from poppy seeds, the test would be reported as negative unless the driver admits illegal use.

DOT noted that most MROs conduct interviews by phone. This change removes the requirement for medical exams that are difficult to arrange.

Biomarker Testing for Drug Testing

The proposal also introduces biomarker testing. Biomarkers are natural substances found in the body. They can help labs confirm that a specimen is genuine and not fake.

DOT said this step would strengthen the integrity of the drug testing process for truck drivers and other transportation workers. Biomarker testing would not be mandatory yet, but it may be added once more laboratories can perform it.

Marijuana and Other Drug Testing Updates

DOT also plans to update how marijuana test results are listed. For urine tests, the analyte name would change from THCA to D9THCC. For oral fluid tests, it would change from THC to D9THC. These updates only affect how results are reported, not how testing is performed.

Other small changes include removing fax number requirements from chain-of-custody forms and correcting references to the Federal Motor Carrier Safety Administration’s Clearinghouse. Collectors for urine and oral fluid specimens would also need to complete training and proficiency testing within 30 days. DOT said this would improve accuracy and reduce errors.

Safety Concerns Behind Drug Testing Expansion

DOT emphasized that fentanyl is now at the center of the opioid crisis. The agency pointed to research showing that fentanyl has been detected in overdose cases, impaired driving investigations, and pain management patients.

Illegally manufactured fentanyl is especially dangerous. Even tiny amounts can cause overdose and death. DOT said, “adding fentanyl and norfentanyl is in the interest of transportation safety” and will help protect truck drivers and the public.

Next Steps

The proposed rule is open for public comment until October 17, 2025. Anyone can submit comments at regulations.gov under docket number DOT–OST–2025–0049.

Once the comment period ends, DOT will decide whether to issue a final rule. If adopted, the changes will apply to all DOT agencies. For the trucking industry, this means the Federal Motor Carrier Safety Administration (FMCSA) would require fentanyl drug testing for all truck drivers.

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