Excess use of mouthwash, more than three times a day, could increase the risk mouth and throat cancers, according to a University of Glasgow study.

Researchers said that poor oral health (dentures and persistently bleeding gums) and irregular dental checkups are other factors that might contribute to upper aerodigestive tract cancer (cancer of the mouth, larynx, pharynx and esophagus).

For the study, the researchers observed 1,962 cancer patients and 1,993 healthy people in 13 centers across nine countries. Other factors known to cause cancers of the mouth and throat like smoking, alcohol and socio-economic aspects were not considered in the study.

Dr David Conway, a senior lecturer at the Dental School, said that instead of using mouthwash, people should regularly brush with a fluoride toothpaste and floss their teeth. He also added that people wearing dentures should also visit the dentist regularly.

 "I would not advise routine use of mouthwash, full stop. There are occasions and conditions for which a dentist could prescribe a mouthwash - it could be that a patient has a low salivary flow because of a particular condition or medicine they are taking," Conway said in a statement.

Conway said that there could be a relationship between unnecessary use of mouthwash and people using the solution to mask the smell of alcohol or smoking. In any case, too much mouthwash was found to be harmful.

The study however, was unable to determine the types of mouthwash used by the participants many years ago.

Professor Damien Walmsley, adviser to the British Dental Association, said that the study does not conclude certain facts.

"It does, however, reaffirm that smoking together with heavy drinking and a poor diet over time are strong risk factors for developing cancers of the oral cavity and oesophagus. Unfortunately, these behaviours cannot be disassociated from people who neglect their oral hygiene and rarely, if ever, visit the dentist, as this study suggests," Walmsley said,Healthmedicinet reports.

"It also highlights that people, who are at risk of developing these cancers, may be using alcohol-based mouthwashes inappropriately to disguise smoking or drinking alcohol," he added.

The finding is published in the journal Oral Oncology.

Mayo Clinic has listed ways to prevent developing throat cancer:

-          Quit smoking.

-          Engage in moderate drinking

-          Choose a balanced diet or healthy eating plan of fruits and vegetables.

-          Limit the number of sexual partners.