There is no scientific evidence that human urine, whether it comes from a man or woman, can kill the bacteria in the mouth that cause bad breath. Urine itself contains bacteria even before leaving the bladder, according to Science News.
Everyone usually has up to 200 species of bacteria in his or her mouth, with certain types releasing ill-smelling gases and other types maintaining oral health, according to Scientific American. Sterilizing the mouth by killing too many bacteria can also cause bad breath. Healthy people have bacteria around their genitals, while a patient with urethritis or other conditions may also have bacteria in the urethra and bladder, which can increase the amount of bacteria in urine, reports Healthline. Drinking milk, green tea or herbal tea is more likely to improve breath, details WebMD.