It is estimated that between 85 and 95% of halitosis cases are mainly caused by a bacterial imbalance or overgrowth in the mouth. These bacteria usually reside on or underneath the gum line, below the surface of the tongue, as well as around or inside teeth.
In general, when halitosis originates in the mouth, there is no particular strain of bacteria responsible for the nasty odours; what causes bad breath is usually a result of very complex interactions between several kinds of bacteria present in the oral cavity.
Usually an excess proliferation of different types of – otherwise beneficial – bacteria occurs. In particular, large numbers of odour producing bacteria are present; these are usually anaerobic bacteria, which are bacteria that thrive in environments where oxygen is deprived.
Anaerobic bacteria metabolise all the waste present within the oral cavity, throat, tonsils, etc. In particular, they metabolise proteins, dead tissue cells, blood or mucous. When bacteria break down this waste, they start producing large amounts of by-products, mostly volatile sulfur compounds (VSCs).
What causes bad breath are precisely these type of gases (VSCs), because they are the ones responsible for some of the most offensive odours. Here are some of the most common:
- Methyl mercaptan (or methanethiol), which smells like rotten cabbage
- Hydrogen sulfide, which smells like rotten eggs
- Dimethyl sulfide, which smells like rotting fruit and vegetables
In addition, it has been found that bad breath does not necessarily derive exclusively from volatile sulfur compounds, but also from other compounds not made of sulfur, most of them also being metabolised by bacteria in the mouth. Here are a few of the most common other compounds:
- Cadaverine, which smells of putrefying flesh (gives corpses their “characteristic scent”)
- Putrescine, which also smells of putrefying flesh
- Butyric acid, which has an acrid smell (rancid butter, parmesan cheese, vomit…)
- Pyridine, which has a fish like odour
In general, it is best to use the term volatile organic compounds (VOCs) or simply, volatile compounds, when refering to the offensive gases released by bad breath sufferers (gases which may or may not contain sulfur).
The second most common area where bad breath can originate from is the upper respiratory tract: the nose, sinuses, tonsils, throat and larynx. Chronic sinus infections, recurrent throat infections such as tonsillitis, tonsil stones (tonsilloliths), rhinitis or post nasal drip are all examples of common infections or conditions that can lead to bad breath. In these cases, it is also the proliferation of VOC-producing bacteria inside the throat, tonsils, nasal passages or sinuses that leads to halitosis.
Halitosis caused by conditions or diseases originating outside the oral cavity is by far much less common than halitosis caused by conditions or diseases originating with the mouth. It is estimated that between 8 and 10% of halitosis cases originate inside the upper respiratory tract (excluding the mouth).
It is not yet fully understood why some people are more prone to oral or respiratory tract bacterial imbalances than others. However, it is clear that some factors and conditions can trigger bacterial overgrowth, so it is important to determine whether any of these may apply so that what causes bad breath can be established.
These are the most common causes of halitosis:
- Oral infections, such as dental decay or an infected wisdom tooth
- Gum disease, such as gingivits or periodontitis
- Dry mouth condition, also called xerostomia
- Poor oral hygiene
- Sinus infections, throat infections, post nasal drip and allergies
- Tonsil stones, also called tonsilloliths
Statistically, bad breath is most often a direct consequence of the accumulation of bacteria underneath the surface of the tongue, and / or a build-up of plaque (therefore, bacteria too) around teeth and below the gum line. Hence we are talking about oral infections, gum disease, dry mouth and poor oral hygiene as the most likely causes of bad breath.
Note that, appart from the mouth, nose, sinuses, tonsils and throat, bad breath can also originate from the stomach. However, statistically it is very unlikely. Halitosis can only originate from the stomach when there is a severe problem with digestion, such as chronic vomiting, chronic indigestion, GERD, acid reflux, IBS, etc. Even in these cases, it is not very likely that undigested food particles can reach the upper part of the esophagus. However, it is possible that saliva composition is altered by poor digestion, causing dry mouth or an acidic environment more prone to bacteria overgrowth, hence bad breath.
In additon, bad breath can also occur as a side effect of certain serious medical conditions, such as diabetes, liver, kidney or lung disease, oral cancer, TMAU, and certain blood disorders, to name a few. Statistically, it is also very unlikely.
It is also worth mentioning the existence of the conditions pseudohalitosis and halitophobia, which are psychological in nature. It is estimated that nearly a quarter of patients seeking professional advice suffer from an exagerated concern of having bad breath and are, in fact, imagining their halitosis. However, the fact that a medical professional may not perceive a patient´s bad breath on a particular day at a particular time should not be a reson to dismiss that person as halitophobic, since it is common for bad breath to vary throughout the day, not to mention the fact that how offensive someone´s breath is, is a highly subjective matter.
A very important factor to be aware is that it is very common for halitosis to stem from multiple causes, so it is crucial that a methodical approach is followed so that all possible underlying causes are identified. Accurate diagnosis as to what is causing bad breath is fundamental so that the most appropriate treatment can be sought.
Since it is often the case that multiple underlying causes are involved, a truly effective and permanent cure involves using a combination of individual strategies, techniques, treatments and remedies which specifically target each and every one of the underlying conditions which are causing the nasty odours.
Hopefully, you have found this article helpful and now have got a better idea of what causes bad breath. What should you do next?
Other articles you may find useful: