The reclassification was determined in November by MedSafe's Medicines Classification Committee which recommended medicines containing opium tincture and squilloxymel be reclassified as prescription only.
Those with dextromethorphan and modified-release paracetamol were also recommended for reclassification as pharmacist only medicine.
It means patients either need to get a prescription from their GP or have their details, including name and address, recorded by the pharmacist.
The affected brands of cough medicine include Gee's Linctus, Dimetapp, Coldrex, Codral, Benadryl, Robitussin, Panadol Cold and Flu Relief, Your Pharmacy, Strepsils [for dry cough] and some Vicks.
A discussion paper on the reclassification cited three cases between 2009 and 2011 of drug abuse or dependence on Robitussin by men aged 22, 31 and 34.
The change, which follows international practice, had to be formally confirmed by the Health Minister's delegate and published in the New Zealand Gazette before it came into force, according to Pharmacy Today.
The notice appeared in the Gazette last Monday but was not widely publicised.
"The email [from Pharmacy Guild] said it was effective immediately," Deng said.
"We had to shuffle the shelves quite fast. I guess there was some discussion we weren't made aware of."
Later that day the Health Minister visited the recently rebuilt pharmacy which, ironically, now offers an "extended range of easy to access health services" through pharmacists including vaccinations, urinary tract infection treatments and oral contraception.
Deng said he expected some patients to be confused or annoyed by the cough medicine changes because they had long been available off the shelf.
"For pharmacist-only medicine we have to record the sale. And some people don't like giving those details.
"I guess it's to make sure people don't come in and buy it all the time. Because dextromethorphan has been known to be abused a little bit."
Pharmacist-only medicine gives the pharmacist a chance to check through questioning whether the person actually needs to see a doctor, or whether their purchase is suspicious if they are buying the medicine too frequently.
Supermarkets that house pharmacies or cough medication have also been affected.