Causes of Breath Odor

Causes of breath odor depend on the type of odor. An overall poor breath odor (halitosis) is often related to lifestyle and oral hygiene reasons, possibly exacerbated by some type of dental disorder. But a number of underlying diseases can also cause halitosis such as respiratory disorders and gastrointestinal disorders.

Types of Breath Odor: Particular types of breath odor have their own specific causes, such as:

Simple Causes of Halitosis: Various simple effects in a person’s life or occupation, or a number of common disorders, can cause halitosis, such as:

Dental Disorders (Halitosis): Some dental disorders that can cause generally “bad breath” (halitosis), can include:

Respiratory Diseases: Various different diseases of the respiratory system, throat, and airways can cause halitosis, such as:

Gastrointestinal Disease Causes (Halitosis): A variety of other different diseases can cause halitosis, through either mechanisms of acid reflux or via obstructions, such as:

Perceived Breath Odor: It is possible that the smell of breath odor may be perceived only by the patient, and cannot be smelled by others, such as in:

  • False breath odor
  • Psychogenic breath odor
  • Olfactory hallucination (smell hallucination)
  • Smell abnormality (olfactory disorder)

Other Causes of Halitosis: Some of the other causes of halitosis include:

Fruity Acetone Breath: Breath that smells “fruity” or like “acetone” is a classic sign of acidosis, which refers to having too much acid in the blood. The list of causes includes:

Read more about: Fruity Breath Odor, Causes of Acidosis.

Musty Breath Odor: Causes of a breath odor that smells “musty” or “mousy” include:

Fecal Breath Odor: Breath that smells like feces is a dangerous symptom usually caused by some type of obstruction in the digestive tract, which is a life-threatening disorder. Example causes include:

  • Gastrointestinal obstruction
  • Gastrointestinal fistula (gastrocolic fistula)
  • Bowel infarction

Ammonia Breath Odor: Breath that smells of ammonia, or smells “fishy” or urine-like, is related to uremia and kidney failure. The various causes include:

Other Odors: Various other types of odors may include:

  • Phenylketonuria (PKU). Usually an abnormal “musty” body odor or sweat odor (of a newborn), rather than breath odor.

Similar Symptoms: See also the causes of these related symptoms:



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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.