Bad Taste in Mouth – Causes of Cacogeusia (Foul Taste Sensation)

Cacogeusia is the medical term for a bad (foul) taste in the mouth. It usually exists on its own and does not necessarily occur when eating or tasting food or drink that does not otherwise taste foul. At times an altered taste sensation, known as dysgeusia, can make food or drink taste foul, although under normal circumstances it is not offensive tasting.

Sense of Taste

Taste is primarily the function of the taste buds although the sense of smell does play a part in the perceiving tastes. The different types of taste receptors can be broadly grouped into the following taste sensations :

  1. Sour – triggered by high concentration of hydrogen ions (acids)
  2. Salty- triggered by ionized salts, especially sodium ions
  3. Sweet – triggered by a wide variety of chemicals, especially organic compounds
  4. Bitter – triggered by a number of different chemicals, especially long chained organic compounds containing nitrogen and alkaloids
  5. Umami”  (Japanese ~ delicious) – often triggered by L-glutamate (meat, aged foods)

The four primary tastes were considered as sour, salty sweet and bitter but now umami taste is also considered as one of the primary tastes. The variations in tastes of different foods is due to a combination of taste sensations being triggered.

With cacogeusia, the bad taste in the mouth is not usually due to psychogenic causes and rather due to some pathology that is offensive in taste and often smell as well.

Causes of Bad Taste in the Mouth

The more common causes of cacogeusia are related to pathology in the mouth. Gastrointestinal causes and disorders of the lung and airways may also be responsible. Halitosis (bad breath) is often seen in these cases, although with cacogeusia due to psychogenic causes and medication, halitosis is usually absent. If cacogeusia is accompanied by cacosmia, which is the perception of offensive odors despite its absence in the environment, upper respiratory tract infections and sinusitis needs to be considered.

Dental Problems

A tooth cavity is probably the most common cause of cacogeusia. The rotting food particles (decomposition) in the cavity causes a bad taste in the mouth and often bad breath as well. Gum diseases, like gingivitis and periodontitis, may also be responsible.

Mouth Problems

Apthous ulcers (mouth sores), oral cavity cancer and other causes of stomatitis are also responsible for cacogeusia. A bad taste in the mouth may not be present at the outset and is usually seen in infectious causes. Conditions of the throat, like tonsillitis and pharyngitis, may also be responsible. Various causes of xerostomia (dry mouth) may result in cacogeusia but this is usually due to the increased risk of mouth and dental infections seen with reduced saliva production.

Gastrointestinal Problems

A number of conditions affecting the gastrointestinal tract may result in cacogeusia. This may either be related to decomposition of food due to impaired motility like in gastroparesis and pyloric stenosis or infectious causes like in gastritis.

Severe cases of GERD (gastroesophageal reflux disease) may also be responsible as partially digested and sometimes decomposed food particles and stomach acid are passed up into the pharynx or mouth. This bad taste is often more prominent in the morning upon waking, and also results in a persistent sore throat in the mornings that ease during the course of the day as well as bad morning breath.

Respiratory Problems

Conditions affecting the airways and lungs may also result in cacogeusia and usually halitosis as well. Most of the causes are infectious in nature. This includes a lung abscess, gangrene, bronchiectasis and tuberculosis.

Other Causes

  • Certain medication like antibiotics, oral contraceptives and some PPIs (proton pump inhibitors) have been implicated in cacogeusia. However, in many instances this may be due to other factors and there is insufficient evidence to verify this as a side effect.
  • Diabetic patients may report a bad taste in the mouth, although halitosis is a more common complaint, and it is usually related to ketacidosis. Infectious stomatitis and dental caries are more likely to occur in a case of uncontrolled diabetes which will result in both halitosis and cacogeusia.
  • Psychogenic causes may also be responsible however, the above mentioned causes need to first be excluded.

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