Contrary to the popular belief that Listerine coined the term halitosis, its origins date to before the products existence, being coined by physician Joseph William Howe in his 1874 book The Breath, and the Diseases Which Give It a Fetid Odor, although it only became commonly used in the 1920s when a marketing campaign promoted Listerine as a solution for "chronic halitosis". The company was the first to manufacture mouth washes in the United States. According to Freakonomics: Listerine "...was invented in the nineteenth century as powerful surgical antiseptic. It was later sold, in distilled form, as both a floor cleaner and a cure for gonorrhea. But it wasnt a runaway success until the 1920s, when it was pitched as a solution for "chronic halitosis"— a then obscure medical term for bad breath. Listerines new ads featured forlorn young women and men, eager for marriage but turned off by their mates rotten breath. "Can I be happy with him in spite of that?" one maiden asked herself. Until that time, bad breath was not conventionally considered such a catastrophe, but Listerine changed that. As the advertising scholar James B. Twitchell writes, "Listerine did not make mouthwash as much as it made halitosis." In just seven years, the companys revenues rose from $115,000 to more than $8 million." Alternative medicine
According to traditional Ayurvedic medicine, chewing areca nut and betel leaf is a remedy for bad breath.
Food debris becomes trapped, undergoes slow bacterial putrefaction and release of malodourous volatiles. Food packing can also cause a localized periodontal reaction, characterized by dental pain that is relieved by cleaning the area of food packing with interdental brush or floss. Acrylic dentures (plastic false teeth) – inadequate denture hygiene practises such as failing to clean and remove the prosthesis each night, may cause a malodour from the plastic itself or from the mouth as microbiota responds to the altered environment. The plastic is actually porous, and the fitting surface is usually irregular, sculpted to fit the edentulous oral anatomy. These factors predispose to bacterial and yeast retention, which is accompanied by a typical smell. Oral infections
Oral ulceration
Fasting
Stress/anxiety
Menstrual cycle – at mid cycle and during menstruation, increased breath VSC were reported in women. Smoking – Smoking is linked with periodontal disease, which is the second most common cause of oral maloduor. Smoking also has many other negative effects on the mouth, from increased rates of dental decay to premalignant lesions and even oral cancer. Alcohol
Volatile foods  – e.g. onion, garlic, durian, cabbage, cauliflower and radish. Volatile foodstuffs may leave malodourous residues in the mouth, which are the subject to bacterial putrefaction and VSC release. However, volatile foodstuffs may also cause halitoisis via the blood borne halitosis mechanism. Medication – often medications can cause xerostomia (dry mouth) which results in increased microbial growth in the mouth. Nose and sinuses
In this occurrence, the air exiting the nostrils has a pungent odour that differs from the oral odour.