The Government has made a big first move to crack down on recreational use of nitrous oxide

New Medsafe advice says nitrous products -- or nangs -- sold for recreational use, fall under the Psychoactive Substances Act, and are now illegal.

Health Minister Dr Shane Reti says Medsafe compliance officers will monitor for recreational and legitimate uses -- like anaesthetics and baking.

He says they'll look to what other countries are doing for how to police it.

Dr Reti says for example in Western Australia, only registered food stores will be able to distribute it -- and they'll take on the international environment for here.