Three people were sent to the city's Royal Gwent Hospital and seven were treated at Friars Walk on Wednesday.
People said they felt unwell after reportedly smelling gas.
The Welsh Ambulance Service said it was actually caused by a "completely harmless" strong glue.
An ambulance was called at 15:35 GMT after a number of people reported feeling unwell at a restaurant in the centre.
Matthew Cann, the service's control manager, said: "Following an update, it was apparently an epoxy resin which was being used by workmen on site.
"It's not a gas leak, it is a resin, a strong glue, and completely harmless apart from dizziness and headaches in some people.
"The seven patients we are holding at the scene are going to be discharged and I would imagine the three patients sent to the Royal Gwent Hospital will be discharged when we update the hospital."
A Wales and West Utilities spokesman said: "Working closely with the fire and rescue service, our engineer found that the smell was not caused by mains gas and left the situation in the hands of the fire and rescue service.
"However, our engineer will remain on site while the fire and rescue service continues its investigations."
A supposed gas smell at a Newport shopping centre which caused several people to feel ill was in fact resin used by workmen, the ambulance service has said.