Plain packaging should be extended to party pills and synthetic cannabis to reduce the appeal of these drugs to young people, a lobby group says.
New Zealand Drug Foundation wants new legislation which regulates synthetic drugs to include stricter rules on packaging in order to make the products "as unsexy as possible".
The Psychoactive Substances Bill was tabled in Parliament last month, and would require drug manufacturers to prove their products were safe, at their own cost, before the drugs could be sold.
The new bill set many restrictions such as a minimum purchase age of 18 for approved psychoactive drugs, and a ban on advertising.
But New Zealand Drug Foundation executive director Ross Bell wanted it to go further. He said that plain packaging should be introduced as part of the legislation to prevent legal battles with the industry in future.
"Because this is a world-first, our view is that we should try to get as much right at the start as possible.
"With tobacco and alcohol, there's a big review every couple of decades with the law, and there's always wailing and gnashing of teeth in those areas.
"Let's try to get [plain packaging] built into the law now, from day one, rather than pick a fight with the party pill industry in five years' time."
Mr Bell said the same rationale for plain cigarette packets could be applied to synthetic cannabis and party pills.
"We don't want to suddenly create this new market which is really attractive. We're trying to make these products as unsexy as possible."
Temporary bans on potentially harmful synthetic products would lapse in August.