Plans are moving forward to convert a portion of an historic house first built more than 200 years ago in Harvard Square into a place for registered patients to purchase medical marijuana products.

The Cambridge Planning Board on Feb. 28 voted in favor of a special permit for Healthy Pharms Inc., to operate a dispensary at The Red House, a restaurant packed tightly among other businesses along pedestrian-friendly Winthrop Street.

The plan was opposed by a smattering of neighbors during a recent public hearing, with some worrying that the dispensary could fast become a place to purchase the drug for recreational use and others claiming it would cause “irreparable” harm to abutters.

But many in Cambridge have been overwhelmingly supportive of the proposal.

Nathaniel Averill, executive director of Healthy Pharms Inc., said the operation in Harvard Square would be discreet and feature tight security, and cater only to patients who rely on the drug to ease ailments.

“I think there are always concerns, no matter where you go,” he said. “But we have done a number of things, and we are trying to work with the local community groups as best we can.”

The Red House, built in 1802, is run by restaurateur Paul Overgaag, who is also Averill’s business partner.

Plans for the dispensary call for downsizing the restaurant and turning the current side entrance into a hallway that would lead to a “mantrap” — a security checkpoint — and then toward the back of the building to a sales floor where medical pot could be purchased only by patients registered with the state.

Part of the restaurant’s second floor, currently devoted to rooms for events and dining, would become offices for dispensary staff and security, Averill said.

The Red House would remain a restaurant with a downstairs dining area, bar, fireplace, and patio space, and continue to serve food.

Averill said the restaurant and the dispensary would be separate entities and that the face of the historic house, with its white trim windows and dark shutters, would not be touched — aside from a few outdoor security cameras.

“We are not changing the outer look of the facility in any kind of way,” he said.

In other words, said Valerio Romano, counsel and compliance officer for Healthy Pharms Inc., “This is not Denver with neon signs.”

Marijuana would not be grown, cultivated, or processed in the building, according to the proposal. That would all be done in Georgetown, where Healthy Pharms Inc., has an existing operation.

Once the Planning Board files its decision with the City Clerk’s office, there is a statutory period during which it can be appealed.

Before it can officially open, the nonprofit must yet win approvals from the state’s Department of Public Health, the agency that regulates medical marijuana facilities, as well as building permits and a certificate of occupancy from Cambridge officials.

Averill said an opening date has not been set for the dispensary, but he and Overgaag hope it’s by the end of this year.

He said having a dispensary in a neighborhood that’s easy to get to via public transportation, like Harvard Square, will benefit registered users.

“It’s great for patient access,” he said. “It’s really the most accessible spot.”

Jesse Kanson-Benanav, chairman of A Better Cambridge, a nonprofit community group, said the city heavily backed the legalization of medical marijuana in 2012 and that putting a dispensary in Harvard Square makes sense.

“Cambridge is an area that should have multiple marijuana dispensaries for patients who need it,” he said. “Medical marijuana is a vital service and it’s high time — no pun intended, I didn’t mean to make that pun — that we have some functioning dispensaries.”

Denise Jillson, executive director of the Harvard Square Business Association, said Overgaag, owner of The Red House, is well-respected in the community and “a known entity.”

She said her board gave full support to the plan, citing the importance of supplying medical marijuana to patients in need.

“Paul is a very responsible business owner,” she said. “It’s in his best interest as a property owner to make sure everything he does is appropriate, because his name is on it.”

City Councilor Marc McGovern, who helped write a new ordinance to expand the areas in the city where dispensaries can operate, said “the big hurdles” have been overcome and wished the nonprofit the best of luck.

“Are there going to be some people against it and who don’t think it’s a good thing? Sure,” he said. “But for the most part, this city has come out overwhelmingly with support for medical marijuana dispensaries. You’ve got to put them somewhere, and Harvard Square is a good a place as any.”