The link: A handful of studies since the late '70s have tied mouthwash that contains ethanol to oral cancer. Investigators theorize that it may make oral tissues more vulnerable to known carcinogens, such as those in cigarettes.
The reality: The evidence against mouthwash is weak, according to the American Dental Association. Studies don't show, for example, that brands with higher alcohol content present a greater risk than those with lesser amounts. Mouthwash is safe when used as directed, says the ADA, which, depending on the product, may mean swishing once or twice daily and not swallowing. People who smoke, have a family history of oral cancer, or have other risk factors may want to choose alcohol-free brands to be on the safe side, the ADA says.