Pseudoephedrine is expected to make an early return to pharmacy shelves.
Medsafe has approved 11 cold and flu medicines containing the medicine, Associate Health Minister David Seymour said.
Pharmaceutical suppliers have indicated they may be able to supply the first products in June, much earlier than original expectations the medicines could be available over-the-counter without a prescription by 2025.
Seymour said the change will bring New Zealand into line with Australia, Canada, the UK and US.
"The government recognised that New Zealanders want these medicines for winter, and we've done our part in achieving this by changing the law swiftly and overseeing a fast approval process by Medsafe.
"The only step left is for pharmaceutical companies to get the medicines to our shores, which they've indicated they can do by winter."
Legislation reclassifying pseudoephedrine from a Class B to a Class C controlled drug passed its final reading this week, with support from all parties.
Seymour said fears pseudoephedrine would be used for methamphetamine production had been misguided and safeguards would remain in place to prevent misuse.
"It will retain its status as a controlled drug and a precursor substance. While restrictions on importing and exporting these medicines are still in place, and New Zealand Police and New Zealand Customs are able to seize illicit products