Halitosis is a commonly reported complaint
Oral malodour (halitosis) is common in people of all ages
Poor oral hygiene is the most common cause
The oral source of halitosis reflects local bacterial production of odiferous sulphides and amines
A range of systemic disorders may rarely cause the problem
Improving oral hygiene, and perhaps tongue cleaning, is usually effective
Patients with symptoms of halitosis in the absence of objective oral malodour may warrant psychological investigation or support
and tonsiliths may also be causes of halitosis. Foreign bodies in the nose can likewise produce a striking odour to the breath.1 Bronchiectasis and other lung infections, such as in cancer, may also cause halitosis.
A range of systemic disorders may rarely cause oral malodour (box 2). The halitosis of such disorders is unlikely to be an early feature of such disease (including undiagnosed type 1 diabetes mellitus) and is an incidental finding during clinical examination. Of interest, Helicobacter pylori infection has been suggested to cause a subjective change in oral odour.3 A range of drugs may rarely cause oral malodour (box 3).
Trimethylaminuria ("fish odour syndrome") is a rare disorder characterised by longstanding oral and body malodour caused by an excess of trimethylamine that produces a pungent ammoniacal odour similar to that of rotten fish. This disorder reflects either defective flavin mono-oxygenase activity (often geneticallydetermined) or an overload of precursors of flavin mono-oxygenase"for example, after choline treatment for Huntington's chorea or Alzheimer's disease.4 Hypermethioninaemia is another rare metabolic disorder that can lead to oral malodour.