Extreme caution's being urged to users of synthetic cannabinoids, especially in Auckland

Multiple hospitalisations in the region have been linked to the substance in the past 24-hours.

High Alert - which issues warnings about dangerous or misrepresented drugs - says it's currently unknown which synthetic cannabinoids are responsible.

But it's very likely present throughout Auckland, and possibly other parts of the country as well.

It advises calling emergency services if someone you know takes this substance and starts to lose consciousness or stops breathing.