When Listerine was first invented in the 19th century, it was touted for its ability to clean floors and cure gonorrhea — two seemingly unrelated things. Today, Listerine is strictly used as a mouthwash.
Now, over a century later, Listerine is getting back to its roots of fighting the STD. According to a study published the in the medical journal Sexually Transmitted Infections, the popular mouthwash does in fact kill gonorrhea bacteria.
If left untreated, gonorrhea — sometimes an asymptomatic bacterial infection — can in some cases cause infertility, sterility and even death.
Scientists at the Melbourne Sexual Health Centre in Australia tested different concentrations of Listerine to determine how effective it is at reducing bacterial counts of gonorrhea in a Petri dish and then compared their results to saline solution. They found that Listerine dilution of up to one in four significantly inhibited the growth of gonorrhea, while the saline solution did not.
The researchers then did a randomized controlled trial of 58 gay or bisexual men who tested positive for gonorrhea in their throats. The volunteers who were asked to gargle with Listerine and saline solution, and just five minutes later had their throats swabbed. Those that gargled with Listerine had much lower proportions of gonorrhea in their throats than those who just used saline solution — a 52 percent to 84 percent difference.
“If daily use of mouthwash was shown to reduce the duration of untreated infection and/or reduce the probability of acquisition of N. gonorrhoeae, then this readily available, condom-less, and low cost intervention may have very significant public health implications in the control of gonorrhoea in [men who have sex with men],” wrote the researchers.
However, scientists are not sure how long these results could last, or even how often the men would have to gargle with Listerine in order to prevent future gonorrhea infections in the throat. The scientists behind the study also pointed out that although the mouthwash may be an effective tool against gonorrhea in the throat, they are unsure of its impact on gonorrhea infections in other parts of the body. Since the study was only conducted on men, Listerine’s effectiveness with women still needs to be tested.
Recently in the United States, gonorrhea rates have gone up. In 2014 alone there were 350,062 reported cases of gonorrhea, which was a 5.1 percent increase from the year before, and a 10.5 percent increase from 2010, according to the Centers for Disease Control and Prevention.
Gonorrhea is also more prevalent in men — in 2014 there were 120.1 reported cases per 100,000 males. The bulk of cases reported were among gay and bisexual men.