Drinkers of wine, sherry and port may be unknowingly breaking the law and consuming small doses of the party drug fantasy, an illegal class B drug.
The revelation has brought calls for wine to be tested to see if there are traces of gamma-hydroxybutyric acid (GHB), or its precursor gamma-butyrolactone (GBL) - the active ingredient in fantasy.
Concerns have also been raised about beauty products containing GHB, which have been sold here for years.
The Ministry of Health has only just been made aware of the issue and is working through how to deal with it.
National Addiction Centre director Doug Sellman said it seemed likely that some wine contained GHB, and called for more research.
"It raises the bizarre conclusion that many wines in New Zealand may, in fact, be technically illegal.
"There's been no research done on New Zealand wines, and only one article in 2005 in the international literature."
The paper found that GHB or GBL occurred naturally in fermenting grapes. It looked at 50 beverages in Britain and found the ingredient in red wine vermouth, sherry, port, red wine and white wine.
The concentration of GHB ranged from 4.1mg per litre to 21.4 mg/l, with the greatest concentration found in red wine; doses as a recreational drug are usually between 500mg and 3000mg.
Dr Sellman said he was not calling for prohibition, but wine-drinkers were essentially using fantasy in small but significant amounts.
"We're not talking about trace amounts. If you drank a bottle of wine, a small but significant part of that intoxication will be from fantasy."
But Dr Keith Bedford, general manager of forensics at Environmental Science Research, said the level of GHB in wine was virtually meaningless.
"You can consider the effects as being very similar to alcohol. Compared to the amount of alcohol in alcoholic drinks, what we're talking about is trivial."
Associate Health Minister Peter Dunne said "there'd be a measure of outrage" if wine was found to be illegal.
"I don't think there's any serious suggestion that people were deliberately breaking the law.
"A fair measure of common sense would need to be applied."
* Gamma-hydroxybutyric acid (GHB), or its precursor Gamma-butyrolactone (GBL) is the active ingredient in fantasy. It is a Class B drug, illegal since 2002.
* The Ministry of Health has been told it is likely wine contains GHB. Some beauty products also contain it.
* Wine drinkers may be unknowingly using an illegal substance.
* It is up to enforcement agencies to take action against importers and distributors of products containing GHB.