It is necessary to understand the cause of halitosis to initiate treatment. Certain diseases that might present with similar features as halitosis include dehydration, diabetes mellitus, liver failure, kidney failure, bronchi or lung infection, tuberculosis, or internal bleeding.
Let’s get one thing straight right off the bat: no one is claiming that Listerine invented bad breath. Human mouths have stunk for millennia, and there are ancient breath freshening solutions to prove it. But, as Esther Inglis-Arkell writes at io9, in more modern days, advertisements for Listerine transformed halitosis from a bothersome personal imperfection into an embarrassing medical condition that urgently required treatment. Treatment that—conveniently—the company wanted to sell.

A physician may recommend antibiotics, tonsillectomy, or other surgical ways to remove the debris. Drinking plenty of water, gargling with salt water, and controlling the urge to smoke are the necessary steps that the patient cannot avoid.
Diet plays a significant role in the development of bad breath. Certain foods, such as garlic and onions, contain sulfur compounds that can be absorbed into the bloodstream and released through the lungs, resulting in bad breath. Other foods, such as coffee and alcohol, can also contribute to bad breath by drying out the mouth.