Bad breath (halitosis) can be divided into systemic causes (which are by far the most common) and oral causes (so-called fetor oris – ‘smell from the mouth’) which are less common.
The systemic conditions which cause halitosis are (in order of frequency):
- Diet - especially dieting, unbalanced diet, high protein diets
- Sinusitis and post-nasal drip
- Tonsillitis
- Inflamed adenoids
- Stomach ulcers
- Lung abscesses
The oral causes are:
- Lack of good oral hygiene
- Periodontal (gum) disease including acute ulcerative necrotising gingivitis (trench mouth)
- Extremely decayed or broken down teeth
- Tooth abscesses and ulcers
- The build up of sulphur-producing bacteria at the very back of the teeth
You can determine whether you have a build-up of bacteria by taking a piece of clean gauze and pushing it to the back of your moth so that you start gagging. Remove the gauze, place it on a clean tissue, cover with a clean bowl and allow to dry out. If the dry gauze stinks you need to visit one of the many fresh breath clinics which will prescribe special mouth rinses and gargles to kill these bacteria. They will teach you how to clean the back of your tongue.
If the gauze does not smell, consult a medical doctor to rule out systemic causes.