Unpleasant odor to the breath. Characteristics - gastrointestinal disorders do not generally cause halitosis, so breath odor does not reflect the state of digestive system or bowel function.

• Inhaled substances
• Ingested substances
• Gingival disease
• Dental disease
• Food fermentation in mouth
• Systemic disease (tonsillitis, pneumonia, bronchiectasis, lung abscess)
• Hepatic encephalopathy
• Diabetic acidosis
• Infectious diseases
• Neoplastic disease of the respiratory tract
• Hypochondriasis