Vendors and attendees at the New England Cannabis Convention expressed frustration over the slow rollout of medical marijuana since voters overwhelmingly approved using pot as a treatment option in 2012.

“It’s way too slow,” said Jill Osborn, the family outreach director at Parents for Pot, a group supporting parents’ choice to use medical cannabis to treat their children’s illnesses. “There are patients in need, people dying, and people living a lesser quality of life because we did not implement this properly.”

Osborn said her 8-year-old daughter has battled epilepsy and many other treatment options proved to be unsuccessful.

“No one cared that she was high on Valium when she was 3,” Osborn said. “It’s not about getting high, it’s about getting better.”

The first medicinal dispensary in Massachusetts opened this past June in Salem, nearly three years after the ballot question passed with 63 percent support. The first dispensary in Boston, which will be located on Milk Street in Downtown Crossing, is scheduled to open about the first of the year.

Jeff Lawrence, co-founder of the New England Cannabis Network, which hosted the two-day convention that began yesterday, said medical marijuana is not an excuse to legalize the drug.

“It’s legitimate medicine and people are realizing this is an alternative option for pain management and a host of other ailments,” he said.

The convention that continues today at the Castle at Park Plaza is expected to draw between 3,000 and 5,000 visitors, Lawrence said.

Cara Crabb-Burnham of the Northeastern Institute of Cannabis is helping to train people interested in a variety of medical marijuana-related fields.

“You can compare it to any other industry because it will be so large,” she said. “We need trimmers, growers, sales, management, consultants, marketing, press … anything another industry needs, the cannabis industry needs right now.”

Most attending the convention said they supported full legalization of marijuana, and people with Bay State Repeal stood outside the entrance collecting signatures to support a 2016 ballot initiative.

Matt Merrill drove up from Warwick, R.I., in part to support a friend who was one of the more than 50 vendors, but also because he believes in medicinal marijuana.

“I have seen the benefits from what it’s done for me,” he said. “I have arthritis in my wrist from a severe injury and if something like that can do good for someone, then why not?

“It’s like alcohol, there’s free will,” he added. “Everyone gets to make their choice.”