The medical use of licorice root dates back to ancient times, but its effectiveness in treating bad breath - or anything else, for that matter - is largely questionable. Studies of licorice's effectiveness in treating ulcers, canker sores, eczema and upset stomach have generally gotten mixed results, according to the University of Maryland Medical Center (UMMC).
Licorice root has been used as an ingredient in candies, foods and traditional remedies for thousands of years. Obtained from the plant Glycyrrhiza glabra, licorice extract has been used as a soothing agent and expectorant for centuries, the medical source notes.
On its own, this fact might lead one to believe that licorice can help ease halitosis, since the production of saliva can flush odor-causing bacteria from the mouth. However, a number of factors make licorice more of a halitosis cause than a cure.
First, licorice is very sweet. The UMMC says that the root is 50 times sweeter than sugar. This is due to the plant's sugars, almost 12 percent of which are glucose and saccharose, according to a study in the Journal of Agriculture and Food Chemistry. These sugars can give oral microbes something to nibble on.
Second, licorice has few proven medical benefits, and can have serious side effects if regularly eaten in large amounts, the UMMC warns. Finally, licorice root smells very pungent when eaten, either as a candy or in root form.
Rather than rolling a wad of black licorice around in the mouth, those with halitosis may consider rinsing with a speciality breath freshener and brushing their teeth thoroughly after every meal.