Waitemata District Health Board suspects there's a new form of synthetic cannabis hitting the Auckland market after a spike in emergency admissions.

Waitakere Hospital admitted 17 people with symptoms between November 13th and 17th.

Emergency Medicine Specialist Dr Kate Allan said the spike suggests the drug is not only more available - but the side-effects are getting worse.

She says typical presentations include heart palpitations, paranoia, anxiety, and depression but patients now being admitted are comatosed and having seizures.

Dr Kate Allen said people are effectively using themselves as lab-rats when they smoke the drug and warns the products have a very different effect to marijuana, aren't safe and are not worth the risk.