Causes of bad breath
Halitosis, or bad breath, most often starts in the mouth.
Poor oral hygiene allows food articles to collect on the surface of the tongue, between the teeth or along the gingival (gum) tissue that surrounds the teeth. Naturally occurring bacteria in your mouth then break down those food particles, releasing chemicals that have a strong odor
Dry mouth: Saliva helps wash food particles from your mouth; thus, people with a dry mouth are at an increased risk of experiencing bad breath. Some medications, mouth breathing and smoking all can contribute to dry mouth
Infections in the mouth, such as dental caries (tooth decay), periodontal (gum) disease or mouth sores related to other conditions may contribute to bad breath. Surgical wounds (from extracted teeth, for example) also can be a source of halitosis
The bacterial film called “plaque” that occurs naturally in your mouth can build up if not removed regularly through good oral hygiene practices. The bacteria in plaque give off an odor that affects your breath.
Diet is a common bad breath culprit. Foods such as garlic and onions, in particular, can foul your breath. Once your food is digested, chemicals that cause odor can be absorbed into your bloodstream and from there into your lungs: these chemicals then are exhaled. Diets high in protein and sugar also have been associated with bad breath.
Health conditions: Bad breath can be a byproduct of certain health conditions. It may result from infections in the nose, throat or lungs; chronic sinusitis; postnasal drip; chronic bronchitis; or disturbances In your digestive system.