Bad Breath: An Overview of Diagnosis and Causes

Unlike other health conditions that aren’t particularly noticeable, bad breath, also known as halitosis, can cause big problems for your social life.

Family, friends, colleagues, customers … every setting that involves face-to-face contact with other people is at risk of being compromised by bad breath. Studies estimate that at least 25% of the general population has chronic halitosis (ongoing bad breath), with approximately 85% of Australians having suffered from another person’s bad breath in a social, professional, or intimate setting [1, 2].

As a result, people who believe they have bad breath sometimes develop defence mechanisms like covering their mouth or turning their head, and may avoid social and intimate situations, leading to anxiety, loneliness and depression [3].

Luckily, most causes of bad breath have easy solutions, so there’s no need to start stress-cramming fresh-breath mints or avoiding your friends. In this article, we’re going to walk you through how to accurately diagnose bad breath, and break down the factors that might be contributing to your chronic halitosis.


Diagnosing Bad Breath

Most bad breath is self-diagnosed. One Japanese study, for example, found that just 20% of surveyed Tokyo inhabitants had bad breath, but that 70% of surveyed Tokyo businessmen regularly self-detected bad breath [4].

In some circumstances, though, our friends, family or colleagues might also alert us to unpleasant oral odours. This can often be a hurtful or traumatising experience, especially when delivered in a careless way. Many studies have found that the psychological effects of being told we have bad breath can linger long after the smell itself is gone [3].

For example, one study participant, a 21-year-old male, stated: “I became conscious in my first dating relationship because she said my breath smelled bad. Since then, I’m becoming very awkward in public. I try to act normal but I’m developing nervous quirks that turn people off” [3].

Another participant, a 34-year-old female, said: “My boyfriend told me [I have bad breath] about seven years ago. Now I am self-conscious and wear a mask when working with clients” [3]. Interestingly, the study’s authors found that this particular woman didn’t even have bad breath – her fear was an ongoing perception formed by an offhand remark [3].

The unfounded fear of having bad breath is known clinically as pseudo-halitosis, and can be even more socially and psychologically damaging than the condition itself [5].

If you think you might have chronic halitosis, don’t self-diagnose – ask a loved one you trust for their opinion, or, alternatively, seek the advice of a medical professional.

Most dentists, hygienists and GPs use organoleptic scoring to diagnose halitosis – in plain English, they smell your breath! The type of smell can often help them diagnose the cause [4]. In some cases, they may also analyse your breath using gas chromatography or portable VSC analysers [4].


Causes of Bad Breath

There are many different causes of bad breath, but they can be divided into two broad categories: physiologic halitosis (bad breath produced by the body’s natural processes) and pathologic halitosis (bad breath occurring as a result of other health conditions). In 90% of cases, halitosis is caused by an oral cavity condition, rather than by problems with the throat, nose, or gut [6].

Let’s take a look at some of the most common causes of bad breath.



Acute halitosis (short-term bad breath) can be caused by eating certain foods, like onions, garlics, certain spices and durian [7]. Onions and garlic both contain sulphur compounds, which, when released via chewing and digestion, can cause bad breath.

Other foods, such as seafood and horseradish, can also cause short-term bad breath.


Tongue Coating

Tongue coating is a major cause of chronic halitosis. Formed by dead epithelial cells, bacteria, blood metabolites, postnasal secretions, and saliva, a tongue coating manifests as a greyish white layer on top of the tongue [8]. The older people get, the thicker and more discoloured their tongue coatings tend to be [8].

Tongue coating causes halitosis because certain anaerobic bacteria that dwell in it produce volatile sulphur compounds (VSCs) [9]. These compounds produce the characteristic ‘bad breath’ smell [9].


Morning Breath

Most of us have, at one point or another, suffered from morning breath. Like the halitosis caused by tongue coating, unpleasant breath in the morning is the result of VSCs released by anaerobic bacteria; saliva flow is reduced overnight, resulting in a build-up of the bacteria [10].

Although classed as a form of short-term halitosis, morning breath can normally be eliminated a good brush and a swig of mouthwash.


Dry Mouth

Dry mouth, clinically referred to as ‘xerostomia’, is a medical condition where your saliva production is reduced, causing your mouth to feel thick, dry and leathery. An estimated 25% of Australia’s older population are affected by dry mouth [4].

Because saliva is essential for removing bacteria build-up and maintaining good oral pH levels, dry mouth can result in chronic bad breath [4].

Learn about how to treat dry mouth here.


Poor Oral Hygiene

Not brushing or flossing regularly can lead to a build-up of putrefying food in and around your teeth, which, in turn, can lead to bad breath [4]. Braces or other dentures can make this problem worse, particularly if they have rough surfaces or are difficult to clean [4].


Periodontitis and Gingivitis

Periodontitis, and its less serious form, gingivitis, are both inflammatory oral conditions that can cause tooth loss. Periodontal ‘pockets’ – where your gums form pockets around the base of your teeth – can harbour periodontal bacteria, which release VSCs and cause bad breath [11].

Both periodontitis and gingivitis are very damaging for your oral health. If you suspect you might have either of these conditions, book a visit to your dentist or hygienist as soon as possible.



Certain types of medication can cause bad breath, either directly or indirectly.

Directly affective drugs cause bad breath either due to the release of blood-borne VSCs, or by encouraging the growth of VSC-releasing anaerobic bacteria [12].

Indirectly affective drugs typically cause bad breath by causing dry mouth, which, as we know, reduces saliva flow and causes chronic bad breath [12].

If you’re suffering bad breath after recently starting a new type or dosage of medication, check with your prescribing physician about any smelly side-effects.



Smoking tobacco or drugs like methamphetamine can seriously affect your oral health – bad breath is just one of many health consequences.

Halitosis from smoking is typically caused by the smell of the smoke itself, as well as by secondary conditions like gingivitis and dry mouth (which can be brought on by prolonged smoking).



Oral infections like stomatitis, intra-oral neoplasia and recurring ulcers can also be responsible for bad breath [4]. Any type of oral condition that changes the pH of your mouth, involves the breakdown of tissue, or provides favourable living conditions for anaerobic bacteria can lead to chronic halitosis.


Throat, Gut & Nose Conditions

Not every case of bad breath is caused by oral problems. In roughly 10% of cases, extra-oral causes like throat, gut and nose conditions are the culprits [4].

Tonsillitis, postnasal drip, sinusitis, lung abscesses, intestinal obstruction, ulcers, renal failure, cirrhosis of the liver, diabetes mellitus and food being caught in the lungs or nose are all relatively common causes of extra-oral bad breath [4].


Treating Bad Breath


Hey! We actually wrote a whole article on natural treatments for bad breath – check it out here.

Getting rid of your bad breath is normally quite easy, but the exact process depends on the cause.

Normally, good oral hygiene, good hydration and avoidance of tobacco/smelly foods will do the trick. Brush twice a day, use mouthwash and floss, and drink enough water.

If your bad breath is caused by another health condition, though, you’ll need to treat the root cause first (your medical practitioner will be able to guide you towards appropriate treatment). In the meantime, use fresh breath products to help banish that unpleasant oral odour.

Although there are plenty of gums and mouthwashes on the market, it’s important to choose a solution that doesn’t dry out your mouth. That’s why we developed Osmist, a natural fresh-breath spray that’s loaded with organic compounds like grapeseed oil, papaya extract and peppermint oil.

Just spray it directly into your mouth every three hours for bad breath relief – the grapeseed oil and papaya extract coat your tongue and mouth to induce saliva production, and the peppermint oil helps fight unpleasant odours. There are no unnatural chemicals, and it comes in a convenient 50ml bottle you can keep in your pocket or handbag.


What are you waiting for? Learn more about Osmist’s breath-freshening abilities here.

Medical information on is merely information and is not the advice of a medical practitioner. This information is general advice and was accurate at the time of publication. For more information about oral care and your individual needs, seek the advice of a qualified medical professional.


[1] Wu, J., Cannon, R. D., Ji, P., Farella, M. & Mei, L. (2019) Halitosis: prevalence, risk factors, sources, measurement, and treatment ‐ a review of the literature. Australian Dental Journal. DOI: 10.1111/adj.12725

[2] Listerine. (2019, April 12) Aussies would prefer to tell a friend their partner cheated than have bad breath. Medianet. Retrieved from:

[3] McKeown, L. (2003) Social relations and breath odour. International Journal of Dental Hygiene. 1(4), 213–217. DOI: 10.1034/j.1601-5037.2003.00056.x

[4] Bollen, C. M. & Beikler, T. (2012) Halitosis: the multidisciplinary approach. International Journal of Oral Science. 4(2), 55–63. DOI: 10.1038/ijos.2012.39

[5] Singh, V. P., Malhotra, N., Apratim, A. & Verma, M. (2015) Assessment and management of halitosis. Dental Update. 42(4), 346–353. DOI: 10.12968/denu.2015.42.4.346

[6] Milanesi, F. C., Kauer, B., Wagner, T. P., Daudt, L. D. & Haas, A. N. (2016) Self-reported halitosis and associated demographic and behavioral factors. Brazilian Oral Research. 30(1). DOI: 10.1590/1807-3107bor-2016.vol30.0071

[7] Porter, S. R. (2011) Diet and halitosis. Current Opinion in Clinical Nutrition and Metabolic Care. 14(5), 463–468. DOI: 10.1097/mco.0b013e328348c054

[8] Seerangaiyan, K., Jüch, F. & Winkel, E. G. (2018) Tongue coating: its characteristics and role in intra-oral halitosis and general health—a review. Journal of Breath Research. 12(3), 034001. DOI: 10.1088/1752-7163/aaa3a1

[9] Ye, W., Zhang, Y., He, M., Zhu, C. & Feng, X.-P. (2019) Relationship of tongue coating microbiome on volatile sulfur compounds in healthy and halitosis adults. Journal of Breath Research. DOI: 10.1088/1752-7163/ab47b4

[10] Snel, J., Burgering, M., Smit, B., Noordman, W., Tangerman, A., Winkel, E. G. & Kleerebezem, M. (2011) Volatile sulphur compounds in morning breath of human volunteers. Archives of Oral Biology. 56(1), 29–34. DOI: 10.1016/j.archoralbio.2010.08.016

[11] Silva, M. F., Cademartori, M. G., Leite, F. R. M., López, R., Demarco, F. F. & Nascimento, G. G. (2017) Is periodontitis associated with halitosis? A systematic review and meta-regression analysis. Journal of Clinical Periodontology. 44(10), 1003–1009. DOI: 10.1111/jcpe.12786

[12] Torsten, M., Gómez-Moreno, G. & Aguilar-Salvatierra, A. (2017) Drug-related oral malodour (halitosis): a literature review. European Review for Medical and Pharmacological Sciences. 21, 4930–4934.

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