Who certifies you
A DOT medical examination must be performed by a certified medical examiner listed on the FMCSA National Registry. Your family physician cannot perform a DOT physical unless they are individually credentialed on that registry. The exam is a fixed protocol: vision, hearing, blood pressure, urine analysis, and a physical examination focused on conditions that bear on commercial driving safety.
Common disqualifying conditions
Insulin-treated diabetes was historically disqualifying but is now permitted under a federal exemption process. Untreated obstructive sleep apnea remains a frequent reason for short-duration medical certificates, with longer certificates issued only after compliance with treatment is documented. Uncorrected vision worse than twenty-forty in either eye, monocular vision without an exemption, hearing loss greater than forty decibels averaged at the 500-, 1000-, and 2000-Hz test points, and uncontrolled hypertension are the most common conditions that result in a denied or short-duration certificate.
How long the certificate lasts
A standard DOT medical certificate is good for up to twenty-four months. Examiners may issue shorter certificates (most commonly for blood pressure, sleep apnea, or other conditions requiring follow-up) at their discretion. You must keep a current certificate on file with your state CDL licensing agency at all times — most states automatically downgrade a CDL to non-commercial within ten business days of certificate expiration.
For drivers preparing for DOT Medical Card Requirements, additional context — including federal manual excerpts, employer hiring practices, and DOT medical guidance — is widely available from industry resources. Continue reading on a recommended industry resource for further detail. Always cross-check anything you read with the current edition of your state CDL manual, since enforcement guidance is updated periodically.