MINNEAPOLIS — Nearly 500 patients suffering intractable pain have registered to buy medical marijuana starting Monday.

Minnesota residents with a handful of serious conditions have been buying medical marijuana for more than a year. But Monday marks a new chapter in Minnesota’s medical marijuana program: Patients with serious pain can being using it, too.

State health officials said Friday that 481 pain patients had pre-registered through their doctors to start picking. State law defines intractable pain as pain that can’t be treated with other methods.

The expansion to include pain patients has been in the works for years. The Legislature directed Minnesota’s health commissioner to decide whether to add intractable pain as a qualifying condition when it legalized medical marijuana in 2014.