Some mouthwashes can contribute to oral cancer and should only be available on prescription, researchers have claimed.

They claimed there was now "sufficient evidence" that mouthwashes containing alcohol contribute to an increased risk of the disease that they should be taken off supermarket shelves and labelled with health warnings.

In a review of the latest studies, the scientists found evidence that the ethanol in mouthwash was allowing cancer-causing substances to permeate the lining of the mouth more easily and therefore cause harm.

Professor Michael McCulloch, chairman of the Australian Dental Association's therapeutics committee and associate professor of oral medicine at Melbourne University, said the alcohol in mouthwashes "increases the permeability of the mucosa" to carcinogens like nicotine.

He added that a toxic breakdown product of alcohol called acetaldehyde that may accumulate in the oral cavity when swished around the mouth is also a carcinogen.

Prof McCullough said: "We see people with oral cancer who have no other risk factors than the use of alcohol-containing mouthwash, so what we've done in this study is review all the evidence that's out there.

"We believe there should be warnings. If it was a facial cream that had the effect of reducing acne but had a four-to-five-fold increased risk of skin cancer, no one would be recommending it."

Some mouthwash can contain as much as 26 per cent alcohol.

The findings, published in the Dental Journal of Australia, said the most popular mouthwashes contained higher concentrations of alcohol than drinks such as wine or beer.

Prof McCullough said: "If you have a glass of wine, you tend to swallow it. With mouthwash you have a higher level of alcohol and spend longer swishing it around your mouth. The alcohol present in your mouth is turned into acetaldehyde."

He said regular alcohol consumption was a cancer risk - but usually did not involve swishing it around the mouth.

Eating while drinking increased salivation which lowered the risks, he said.

Oral cancer is a mutilating disease that afflicts thousands of people each year and kills half of them within five years of being diagnosed.

Smoking and alcohol consumption are well-established risk factors, but the use of mouthwash containing alcohol is more controversial.

Prof McCullough and co-author Dr Camile Farah, director of research at the University of Queensland's School of Dentistry, recommended mouthwash be restricted to "short-term" medical use or replaced by alcohol-free versions.

Dr Neil Hewson, of the Australian Dental Association, said: "It hasn't actually been established there is a direct relationship between mouthwashes with alcohol and oral cancer."

He said if people floss their teeth, brush properly and have a good diet they should not need mouthwash at all. The Daily Telegraph 12th January 2009.

Haynesdental note: If you are worried about your mouthwash then please feel to mention it to the dentist next time you come in. We have plenty of choice of mouthwashes on sale in the surgery and, where appropriate, we may be able to recommend an alcohol free alternative.