Supporting Families in Mental Illness manager Jackie McKenzie said the service, funded by the Southern District Health Board, had offered support in South Dunedin for 38 years and helped up to 180 people with mental illness.
A store selling synthetic cannabis and cigarettes opened two doors down two weeks ago, she said.
Most mornings, about six people were waiting for the shop to open at 8am, she said.
''While we understand they are not doing anything illegal, we do not want it on our doorstep. It's difficult for our families and members to walk past that.''
People with mental health issues were more susceptible to using synthetic cannabis.
''Often drugs can trigger schizophrenia, psychosis and bipolar.''
Many members were overcoming a synthetic cannabis habit and the store location tempted past users.
''It's like taking a gambler to the casino for dinner and telling them they can't gamble.''
The health board cannot object to an interim licence, so a community meeting had been planned for September 17 at King's High School.
''To get the community momentum going, so we can lobby the council, because the council can set the policy.''
From October, the council could create an exclusion zone policy to outlaw the sale of synthetic cannabis near schools, churches or a ''sensitive place'' such as the mental health organisation.
''We don't have to lie down and do nothing about it because ... we can lobby the council.''
Presenters at the forum would include the proactive policing team, a former synthetic cannabis user and Mosgiel mother Carol Pine, whose son David struggled with K2 addiction.
The store owners had bought the shop after new legislation prevented them selling synthetic cannabis in a dairy in King Edward St.
The shop owner declined to talk to the Otago Daily Times.
A salesman for the store, who wanted to remain anonymous, said the shop had been selling synthetic cannabis and tobacco for three weeks.
The store had been visited by police and nothing illegal had been found, he said.
The busiest time for the shop was immediately after the payday of customers, he said.
