Why your DOT card keeps getting shortened to three months

If you drive commercially and your medical certificate keeps coming back for three months instead of two years, blood pressure is the most likely reason. It is also, of all the things that shorten a card, among the most fixable.

What the thresholds actually are

The FMCSA guidance a certified medical examiner works from breaks down roughly like this:

• Under 140/90 — you can be certified for the full two years.
• 140/90 to 159/99 — generally a one-year certificate. You are expected to get it under control before the next exam.
• 160/100 to 179/109 — generally a one-time three-month certificate, then a one-year certificate if you bring it under 140/90.
• 180/110 or higher — you cannot be certified until it comes down. Once it is under 140/90, a six-month certificate.

Before your exam

None of this is a reason to try to game the reading, and an examiner will usually recheck. But several things genuinely raise blood pressure on the day and are worth avoiding:

• Take your medication as prescribed, including on exam day. Drivers sometimes skip it because they think it looks better. It does the opposite.
• Skip caffeine for a few hours beforehand. Coffee and energy drinks can add meaningfully to a reading.
• Do not smoke or vape in the half hour before.
• Sit quietly for five minutes before the reading. Walking in from the lot and sitting straight down inflates it.
• Empty your bladder. A full bladder measurably raises blood pressure.

The part that actually matters

A short card is the system telling you something. High blood pressure does not feel like anything until it causes a stroke, kidney damage or heart failure — which is precisely why it goes untreated for years in people who feel completely fine.

The fix is rarely dramatic. For most drivers it is one medication, sometimes two, adjusted over a few months, plus the parts of the job that work against you: the sitting, the sodium in truck-stop food, the interrupted sleep. Untreated sleep apnoea drives blood pressure up hard, and it is very common in this line of work.

If you only ever see a clinic for the exam itself, nobody is managing the underlying problem. Getting an actual primary care provider — ideally one who also understands the DOT standard — is what turns a three-month card back into a two-year card.