Drivers conflate them constantly — understandably, since both happen around the same clinic visit. But the urine cup at your physical and a DOT drug test are governed by different rules, ask different questions, and carry different consequences. This page separates them. Verdicts about drug testing are outside this department's scope; the separation itself is the service.
The checker reads your verdict. The Kit gets you through the exam: documentation packets for your condition, the two 45-day form clocks run as a calendar, the official medication form packet, waiting-period calendars, failure recovery, and the examiner phone script.
| The medical examination (Part 391) | Drug & alcohol testing (Part 40 / Part 382) | |
|---|---|---|
| Question it asks | Are you medically qualified to operate safely? | Is a prohibited substance present in the specimen? |
| The urine involved | A dipstick screening for protein, blood, sugar, specific gravity — health markers | A laboratory drug panel with chain of custody and Medical Review Officer review |
| Who decides | The certified medical examiner, against the standards in 391.41 | The laboratory and the Medical Review Officer, under Part 40 procedures |
| Marijuana | Schedule I use also violates the medical standard (b)(12) | A THC positive is a testing violation regardless of state law or product labels — including CBD products with undisclosed THC |
| A prescribed medication | Judged under the (b)(12)(ii) exception: prescriber advises, examiner decides | Disclosed to the Medical Review Officer; a legitimate prescription is evaluated under Part 40's own process |
This department computes medical-standard verdicts only. If your question is about a testing situation — a positive, a refusal, a return-to-duty process — that is a different playbook (and for Clearinghouse return-to-duty questions, our sister site ReturnToDuty covers that road).
Federal source: 49 CFR Part 391 (medical); 49 CFR Part 40 & Part 382 (testing) · Rules checked October 2026