As early as 1879, Listerine manufacturers already claimed that the disinfectant can be used as treatment for gonorrhea, a sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae.

Now, after more than 100 years, scientists have found evidence suggesting that the popular mouthwash can indeed kill gonorrhea bacteria.

Listerine Controls Gonorrhea Bacteria

In a new study published in Sexually Transmitted Infections on Dec. 20, researchers conducted a randomized controlled trial to test claims that Listerine can be used as treatment for gonorrhea. They found that the mouthwash can indeed help control gonorrhea bacteria in petri dishes and even in people's mouth and throat.

The findings suggest that daily use of the mouthwash may provide a cheap and easy means to reduce the spread of the sexually transmitted disease.

Listerine vs. Salt Water Solution

Study researcher Eric Chow, from the Melbourne Sexual Health Centre, and colleagues tested Listerine Cool Mint and Total Care variants, both of which are composed of 21.6 percent alcohol, in laboratory experiments and found that these reduced levels of gonorrhea bacteria. A salt water solution, however, did not.

The researchers then proceeded with a clinical trial that involved 58 men who have tested positive for gonorrhea in their mouths or throats. The men were randomly assigned to rinse and gargle using either Listerine or saline solution for one minute.

Results revealed that the proportion of viable gonorrhea in the throat of those who used Listerine was lower at 52 percent compared with 84 percent among those in the salt solution group. After five minutes, the men in the Listerine group were found to have less chances of testing positive for gonorrhea in the throat compared with those who gargled with salt solution.

Listerine Effect On Transmission Of Gonorrhea To Other Body Parts

Researchers said that they are not sure how long the results would last or how long men need to gargle and rinse with the mouthwash to prevent future infections of gonorrhea in the throat.

While Listerine may significantly reduce the levels of bacteria in the mouth and throat, it also remains unclear how the mouthwash would affect transmission of the STD to other parts of the body such as the anus and urethra.

"This data suggest Listerine, significantly reduces the amount of N. gonorrhoeae on the pharyngeal surface. With daily use it may increase gonococcal clearance and have important implications for prevention strategies," Chow and his colleagues wrote in their study.

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