Halitosis, oral malodor (scientific term), breath odor, foul breath, fetor oris, or most commonly bad breath are terms used to describe noticeably unpleasant odors exhaled in breathing whether the smell is from an oral source or not.
Halitosis has a significant impact - personally and socially on those who suffer from it or believe they do (halitophobia), and is estimated to be the 3rd frequent reason for seeking dental aid, following tooth decay and periodontal disease.
In most cases (85-90%), bad breath originates in the mouth itself. The intensity of bad breath differs during the day, as a function of oral dryness, (which may be due to stress or fasting), eating certain foods (such as garlic, onions, meat, fish and cheese), smoking and [[alcohol consumption and health|alcohol consumption. Because the mouth is dry and inactive during the night, the odor is usually worse upon awakening ("morning breath"). Bad breath may be transient, often disappearing following eating, brushing one's teeth, flossing, and rinsing with specialized mouthwash.