Retailers and business owners in Auckland's CBD say a spike in synthetic cannabis use is creating a threatening atmosphere in the area.
Police and the chief coroner revealed on Friday that seven people had died in the past month after using the drug.
The surge in the drug's use has been described as "unprecedented", and ambulance staff told Herald they'd seen up to 20 users a day suffering its life-threatening effects.
Robert Jones Holdings Limited New Zealand general manager Greg Loveridge said in the past six months problems with drugs, antisocial behaviour and begging on Queen St had risen sharply.
His company owned two buildings on Queen St, and was scrambling to respond to frightening behaviour that had left staff feeling unsafe.
"The female staff don't feel safe on the street, visiting executives from overseas don't feel safe walking back to their hotel after dinner.
"People have managed to get into the building and gone to sleep in the meeting rooms. I've had people try to harass my staff.
"Our retailers have told us they've seen clear drug dealing, the exchange of money in the street, but the police are doing nothing about it.
"It's just not acceptable for a civilised society."
Staff and shop workers have been verbally abused or physically threatened.
"Just this weekend, we had staff feeling unsafe in a shop," Loveridge said.
"The shop assistant was confronted by a man on drugs who walked in off the street, and made aggressive movements towards her and was yelling at her.
"I've seen people urinating in the streets.
"[Drug use] was happening outside our building just the other day, a very rough group of older men.
"But you call the police, and they take at least half an hour to get there."
Loveridge said police numbers and resources needed a boost, so they could crack down on the issue.
Heart of the City chief executive Viv Beck said their members had similar problems, and the building issue needed to be dealt with firmly and quickly.
"We've expressed a view that we need to see a really strong police presence on city streets, because it does make a difference to the feeling of safety.
"I saw someone yesterday who wasn't even able to walk properly. They had to be helped.
"These are things you wouldn't expect to see in the middle of a city.
"It can make people feel unsafe, visitors and staff, and that's where it becomes concerning for business."
Beck said the changes being driven by illegal synthetic cannabis were tragic.
The Auckland Council has not yet responded to a request for comment.