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Halitosis (Bad Breath) - 1st of two parts discussing causes of bad breath

Posted by Eamonn Brady on

Halitosis (Bad breath)

Part 1


Up to 50% (22 to 50%) of the population suffer from bad breath and approximately half of these experience a severe problem leading to personal and social discomfort and social embarrassment.  The “mouth air” of those suffering from more severe halitosis is tainted with compounds including hydrogen sulphide, methyl mercaptan and organic acids leading to foul smelling air.



The source of the bad odour is located within the oral cavity in approximately 90% of cases of halitosis meaning only a small percentage of cases are due to non-oral causes such as a serious underlying medical condition which warrants immediate referral to a doctor (eg.) Diabetes


The tongue is considered the biggest source of bad breath and is considered the main cause in up to 90% of cases by some experts; so other causes like gingivitis are considered a cause in only a fraction of causes compared to tongue hygiene.


Oral microorganisms most likely to cause halitosis are gram-negative bacteria species which includes likes of treponema denticola, porphyromonas gingivalis, prevotella intermedia, bacteroides loescheii, Enterobacteriaceae and fusobacterium nucleatum (this oral bacteria list is not exhaustive).


Common Causes

  • Failing to brush teeth twice daily
  • Improper cleaning of dentures
  • Bad breath in morning. This affects most people and dry mouth is the most common cause
  • Alcohol: Alcohol causes dehydration and less saliva production leading to bad breath
  • Smoking: this is often called “smokers’ breath” which is a stale scent caused by the scent of cigarette smoke lingering in the mouth and the chemicals from cigarette smoke mixing with saliva
  • Certain foods and drinks such as onion and garlic or coffee and acidic fizzy drinks
  • Infection (more below)

More specific causes

  • Tongue bacteria: Considered one of the main causes of bad breath. It can be caused by catarrh from the back of the throat and nasal area. It is more often caused by a general build-up of oral bacteria sue to poor dental hygiene. Brushing the tongue with toothpaste (especially if coated) can help. A tongue scraper or cleaner may be used in more severe tongue coating. Despite the tongue being considered the biggest factor in halitosis, simple general oral hygiene measures described later such a regular teeth brushing, flossing, and staying well hydrated will minimise build up of bacteria in all areas of the mouth including the tongue (not just the gums and teeth)
  • Gum disease (gingivitis): due to poor oral hygiene. Bacteria in plaque cause a bad odour
  • Tooth decay: like the bacteria that cause food to break down (creating plaque) and causing gingivitis, the bacteria trapped in a decaying tooth can emit a foul smell
  • Trapped food: Food getting caught between the teeth getting broken down by bacteria
  • Dry mouth: Poor saliva flow means food debris is less likely to get washed away..
  • Acid reflux from the stomach: These acids have a sour odour causing bad breath
  • Diabetes: Diabetics are more prone to high blood sugar levels meaning higher glucose levels in saliva which promotes oral bacteria growth (glucose is a food source for bacteria) leading more dental plaque. Well controlled diabetes and good oral hygiene reduces this risk in diabetes
  • Chest infection: phlegm or mucus infected with bacteria or viruses that a coughed up can have a smell
  • Other infections: Tonsil, throat, and sinus infection: the bacteria or viruses involved can emit a foul smell
  • Other chronic conditions: Certain lung conditions, kidney and liver disease, chronic irritation of the stomachand oesophagus, and autoimmune disorders such as Sjogren disease can cause halitosis.

To be continued…next week I discuss treatment

For comprehensive and free health advice and information call in to Whelehans, log on to or dial 04493 34591 (Pearse St) or 04493 10266 (Clonmore). Email queries to Find us on Facebook.


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