According to the Canada/U.S. Medical Reciprocity Agreement commercial drivers with a history of serious medical conditions are to be issued a "W" code, or Class D licence.
The ministry says it recently sent out letters to truckers notifying them of the change that goes into effect next month.
“Starting May 2013, an indicator code “W” will be visible on your license card and on your driving record," reads a copy of the letter obtained by CBC News.
But according to the CBC's Mike Crawley, many of those who have been slapped with the restriction simply haven't submitted the required paperwork.
"Most of them are actually faced with the restriction because they failed to file their medical reports on time," said Crawley, adding that those records are required every 3 to 5 years.
According to the ministry approximately 41,000 people have had their licences downgraded to a W code for that reason.
Drivers who submit their medical records could potentially have the "W" code lifted from their licence.
Ministry spokesperson Bob Nichols said commercial drivers with a hearing impairment, monocular vision, insulin-dependent diabetes, and/or a history of epilepsy or seizures all fall under the medical conditions requiring a code "W" licence be issued.
Under the bilateral agreement, U.S. commercial drivers are similarly issued a code "V" licence restricting them from driving north of the border.