National Poisons Centre toxicologist Leo Schep says the Government's plans to restrict the sale of the synthetic cannabis product Kronic are just window-dressing and it should be banned.
The Government is moving to make the drug a restricted substance, meaning it will not be able to be sold alongside alcohol or from places such as sports clubs or cars.
Mr Schep, who has been monitoring calls to the poisons centre since October, says the number has increased from about five a month to 10, with 20 expected for June.
He says there have been no deaths from Kronic, but the side-effects - which include increased heart rate, drowsiness, vomiting and chest pain - are alarming.
Mr Schep says Kronic is more potent than marijuana but so little is known about its long-term effects that "it should not be available at all - period".