Also known as bad breath.

A symptom in which a noticeably unpleasant breath odor is present.

It can be associated with anxiety, depression and symptoms of obsessive compulsive disorder.

Affects about 30% of people, with estimates varying from 6% to 50% of the population.

Bad breath may severely affect the lives of some 0.5–1.0% of the adult population.

Concerns of bad breath may be divided into genuine and non-genuine cases.

Of those who have genuine bad breath, about 85% of cases come from inside the mouth in patients with bad breath.

The most common causes are odor producing biofilm on the back of the tongue, below the gumline, and in the pockets created by gum disease between teeth and the gums.

Tongue bacteria produce malodorous compounds and fatty acids.

Tongue bacteria account for 80 to 90% of all cases of mouth-related bad breath.

Naturally occurring bacteria occur in large numbers and are often found on the posterior dorsum of the tongue, where they are relatively undisturbed by normal activity.

This biofilm results in the production of high levels of foul odors produced mainly due to the breakdown of proteins into individual amino acids, followed by the further breakdown of certain amino acids to produce detectable foul gases.

The posterior dorsum of the tongue is relatively dry and poorly cleansed, and its convoluted microbial structure provides an ideal habitat for anaerobic bacteria.

Anaerobic bacteria flourish under a continually-forming tongue coating of food debris, dead epithelial cells, postnasal drip and overlying bacteria, living and dead.

The anaerobic respiration of such bacteria yield either the putrescent smell of indole, skatole, polyamines, or the rotten egg smell of volatile sulfur compounds (VSCs) such as hydrogen sulfide, methyl mercaptan, allyl methyl sulfide, and dimethyl sulfide.

The bacteria that cause gingivitis and periodontal disease are invariably gram negative and capable of producing volatile sulfur compounds..

Gram negative bacteria, the cause of gingivitis and periodontal disease produce volatile sulfur compounds.

Of the volatile sulfur compounds, methyl mercaptan is known to be the greatest contributor in halitosis that is caused by periodontal disease and gingivitis.

The presence of halitosis-producing bacteria on the back of the tongue is not the same as tongue coating.

White tongue coating is present in most people with and without halitosis.

A visible white tongue coating on the front of the tongue does not always equal the back of the tongue as an origin of halitosis.

A white tongue is considered a sign of several medical conditions.

With periodontal disease there is a sixfold prevalence of tongue coating compared with normal subjects.

Halitosis sufferers have significantly higher bacterial loads in the posterior ton compared to individuals without halitosis.

Volatile sulfur compounds are associated with oral malodor levels.

Other parts of the mouth may also contribute to the overall odor, but are not as common as the back of the tongue.

These locations include: inter-dental and sub-gingival niches, faulty dental work, food-impaction areas in between the teeth, abscesses, and unclean dentures.

The level of volatile sulfur compounds on breath is positively correlate with the depth of periodontal pocketing, the number of pockets, and whether the pockets bleed when examined with a dental probe.

Volatile sulfur compounds may contribute to the inflammation and tissue damage of periodontal disease.

Not all patients with periodontal disease have halitosis, and not all patients with halitosis have periodontal disease.

Another possible symptom of periodontal disease is a

Bad taste in periodontal disease, does not necessarily accompany a malodor that is detectable by others.

Individuals with periodontal disease are more likely to suffer from halitosis than the general population, but halitosis is more strongly associated with degree of tongue coating than with the severity of periodontal disease.

Oral viral infections like herpes simplex and HPV may also contribute to bad breath.

The remaining cases are believed to be due to disorders in the nose, sinuses, throat, lungs, esophagus, or stomach.

Rarely, bad breath can be due to an underlying medical condition such as liver failure or ketoacidosis.

Non-genuine cases occur when someone feels they have bad breath but someone else cannot detect it.

The treatment depends on the underlying cause.

Initial treatments include tongue cleaning, mouthwash, and flossing, the use of mouthwash containing chlorhexidine or cetylpyridinium chloride.

Treating underlying disease such as gum disease, tooth decay, or gastroesophageal reflux disease may help.

Concern about tooth decay, gum disease and bad breath are the 3 leading reasons for people to seek dental care.

It occurs more commonly as people age.

Affected individuals may be stigmatized.

More than $1 billion per year is spent on mouthwash to treat the condition.

Eating certain foods: garlic, onions, meat, cheese, and fish and smoking and consuming alcohol may intensify bad breath.

The mouth is exposed to less oxygen and is inactive during the night, making the odor to be usually worse upon awakening, known as morning breath.

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

Chronic bad breath, affects some 25% of the population in varying degrees.

Normally gingival crevices, the small grooves between teeth and gums, are present in health.

These gingival crevices may become inflamed when gingivitis is present.

Periodontal pockets usually accompany periodontal disease, and is a common cause of halitosis.

Anaerobic bacteria waste products growing below the gumline have a foul smell and can produce a very intense bad breath.

Removal of the subgingival tartar or hard plaque,and friable tissue improves mouth odor.

Other causes of bad breath include:

Carious lesions, which cause localized food impaction and stagnation.

Recent dental extraction sockets, which fill with blood clot, and provide an ideal habitat for bacterial proliferation

Interdental food packing

Acrylic denture inadequate hygiene predispose to bacterial and yeast retention, which is accompanied by odor.

Oral infections

Oral ulceration



Menstrual cycle



Volatile foods-onion, garlic, durian, cabbage, cauliflower and radish.


Nose and sinuses

Tonsils-Approximately 3% of halitosis cases were related to the tonsils.



There are a few systemic medical conditions that may cause foul breath odor:

Fetor hepaticus:

Lower respiratory tract infections

Kidney infections and kidney failure.



Diabetes mellitus.

Metabolic conditions

One quarter of the people seeking professional advice on bad breath have an exaggerated concern of having bad breath, known as halitophobia, delusional halitosis, or as a manifestation of olfactory reference syndrome.

They are sure that they have bad breath, although many have not asked anyone for an objective opinion.

There are physical and chemical means to decrease the numbers of bacteria to mask the smell, or chemicals to alter the odor creating molecules.

Individuals that use tobacco products should stop.

There is no evidence that dietary changes or chewing gum benefit halitosis.

Brushing the teeth may help, as flossing, but evidence of benefit from tongue cleaning is insufficient.

Mouthwashes often contain antibacterial agents that may help.

Gum disease and cavities should be treated.

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