Drink driving charges have been dropped against a woman in New York because of an unusual defence: Her stomach is a "brewery".

The defendant's lawyer, Joseph Marusak argued that his client had gut fermentation syndrome, also known as auto-brewery syndrome, reports said.

It is a rare condition where the digestive system has high levels of yeast and converts high carbohydrate food into alcohol.

While others with the syndrome have been diagnosed because they became drunk without drinking alcohol, Mr Marusak said that his client have never felt tipsy and thus was not aware she had the syndrome.

The woman was pulled over for erratic driving on Oct 11, 2014, when a breathalyser test measured her blood alcohol content at 0.33 per cent, news agency UPI said.

The legal threshold for drunkenness in New York is 0.08 per cent. Police said she admitted to drinking three cocktails earlier in the day.

In order to prove that she had the condition, the woman was watched by two nurses and a physician's assistant for a day to make sure she did not drink any alcohol.

At the end of the day, she had a blood-alcohol content of 0.36 per cent, said Mr Marusak.

The woman, who cannot be named due to reasons of medical confidentiality, had her case dismissed on Dec 9.

The first case of auto-brewery syndrome was documented in 2013 by Dr Barbara Cordell of Panola College in Texas.

She is co-author of a study documenting a man who was constantly drunk for five years. He was treated with anti-fungal medication.

Unlike them, most of us are not natural breweries, so don't drink and drive on New Year's Eve!