Believe it or not, Listerine mouthwash has been around since 1879, although at that time it was used as an antiseptic during surgery. Apparently it has also been marketed as a cleaning product and as a treatment for gonorrhea. It came into its own as a mouthwash in 1914 and hasn't looked back. Standing the test of time, today it is a top selling brand in the United States and other markets, and has achieved the approval of the American Dental Association, an achievement not to be taken lightly.
Listerine mouthwash now comes in a variety of flavors, mostly variations of mint but also citrus flavor, and formulations include ingredients for tartar control and tooth whitening. Listerine spray, a little spray bottle that can be carried in the pocket, appeared on the market in about 2005. Testing of the product has supported the claim that Listerine mouthwash effectively kills oral bacteria, reduces buildup of plaque, and helps prevent gingivitis. There's no question that Listerine is one of the top products in its class for treating bad breath.
Active ingredients in Listerine include thymol, eucalyptol, methyl salicilate, and menthol. It is interesting that, though the product is very effective, it does not contain chlorhexidine, cetylpyridinium chloride, chlorine dioxide, or any of the other chemicals so ubiquitous in other brands of mouthwash. If it were not such a long standing commercial brand, we would probably consider it a natural remedy for bad breath. It does contain one inactive ingredient of concern, however, as does Listerine spray: alcohol.
The alcohol in Listerine mouthwash is added to dissolve the other ingredients, and to aid penetration of oral plaque on the teeth. In Listerine spray it probably chiefly serves the first purpose. Alcohol does something else, however, that is not good: it dries out the tissues of your mouth. Drying is not good because saliva is one of our main natural defenses against overgrowth of the bacteria that cause bad breath. A dry mouth is usually a malodorous mouth. Many people would recommend, then, that you stay away from mouthwashes and other oral products that contain alcohol. It may be more of a problem with Listerine spray than with the wash: a blast of alcohol into the mouth numerous times during the day, when you are not otherwise brushing or rinsing, is sure to have more of a drying effect. (And by the way, use of an alcoholic breath freshener can cause you to fail a highway breathalyzer test, should you be unfortunate enough to find yourself in that position.)
Though the issue with alcohol is a valid one, Listerine mouthwash works for many people, so it is not a fatal flaw. If you're searching for a trusted breath freshener, by all means try it. If you're disappointed in the results, or if you would rather stay away from the alcohol based brands (Listerine is by no means the only mouthwash to include alcohol), there are lots of other products to try.