[1] Concern about bad breath is the third most common reason people seek dental care, after tooth decay and gum disease.

The most common causes are odour producing biofilm on the back of the tongue or other areas of the mouth due to poor oral hygiene.

These locations are, in order of descending prevalence, inter-dental and sub-gingival niches, faulty dental work, food-impaction areas in between the teeth, abscesses, and unclean dentures.

[7] Oral based lesions caused by viral infections like herpes simplex and HPV may also contribute to bad breath.

The intensity of bad breath may differ during the day, due to eating certain foods (such as garlic, onions, meat, fish, and cheese), smoking,[8] and alcohol consumption.

Since the mouth is exposed to less oxygen[medical citation needed] and is inactive during the night, the odour is usually worse upon awakening ("morning breath").

Bad breath may be transient, often disappearing following eating, drinking, tooth brushing, flossing, or rinsing with specialized mouthwash.

[10] Tongue bacteria produce malodourous compounds and fatty acids, and account for 80 to 90% of all cases of mouth-related bad breath.

[11] Large quantities of naturally occurring bacteria are often found on the posterior dorsum of the tongue, where they are relatively undisturbed by normal activity.

Removal of the subgingival calculus (i.e. tartar or hard plaque) and friable tissue has been shown to improve mouth odour considerably.

The bacteria that cause gingivitis and periodontal disease (periodontopathogens) are invariably gram negative and capable of producing VSC.

There are a few systemic (non-oral) medical conditions that may cause foul breath odour, but these are infrequent in the general population.

[21] One popular home method to determine the presence of bad breath is to lick the back of the wrist, let the saliva dry for a minute or two, and smell the result.

If bad breath is persistent, and all other medical and dental factors have been ruled out, specialized testing and treatment is required.

[24] The Miyazaki et al. classification was originally described in 1999 in a Japanese scientific publication,[25] and has since been adapted to reflect North American society, especially with regards halitophobia.

[24] Any halitosis symptom is potentially the sum of these types in any combination, superimposed on the physiologic odour present in all healthy individuals.

Firstly, halitosis is subject to societal taboo and stigma, which may impact individuals' willingness to take part in such studies or to report accurately their experience of the condition.

[34] The earliest known mention of bad breath occurs in ancient Egypt, where detailed recipes for toothpaste are made before the Pyramids are built.

The 1550 BC Ebers Papyrus describes tablets to cure bad breath based on incense, cinnamon, myrrh and honey.

[36] Alcohol-containing mouthwashes are now thought to exacerbate bad breath as they dry the mouth, leading to increased microbial growth.

[12] Early Islamic theology stressed that the teeth and tongue should be cleaned with a siwak, a stick from the plant Salvadora persica tree.

[12] This traditional chewing stick is also called a Miswak, especially used in Saudi Arabia, an essentially is like a natural toothbrush made from twigs.

The general population places great importance on the avoidance of bad breath, illustrated by the annual $1 billion that consumers in the United States spend on deodorant-type mouth (oral) rinses, mints, and related over-the-counter products.

An instinctive aversion to unpleasant odours may function to detect spoiled food sources and other potentially invective or harmful substances.

Although reports of bad breath are found in the earliest medical writings known, the social stigma has likely changed over time, possibly partly due to sociocultural factors involving advertising pressures.

Contrary to the popular belief that Listerine coined the term halitosis, its origins date to before the product's existence,[42] being coined by physician Joseph William Howe in his 1874 book The Breath, and the Diseases Which Give It a Fetid Odor,[43][44] although it only became commonly used in the 1920s when a marketing campaign promoted Listerine as a solution for "chronic halitosis".

But it wasn't a runaway success until the 1920s, when it was pitched as a solution for "chronic halitosis"— a then obscure medical term for bad breath.

Listerine's new ads featured forlorn young women and men, eager for marriage but turned off by their mate's rotten breath.

"[45]According to traditional Ayurvedic medicine, chewing areca nut and betel leaf is a remedy for bad breath.

[48] Practitioners and purveyors of alternative medicine sell a vast range of products that claim to be beneficial in treating halitosis, including dietary supplements, vitamins, and oral probiotics.