Morning time Saliva flow almost stops during sleep and its reduced cleansing action allows bacteria to grow, causing bad breath. Certain foods Garlic, onions, etc. Foods containing odor-causing compounds enter the blood stream; they are transferred to the lungs, where they are exhaled. Poor oral hygiene habits Food particles remaining in the mouth promote bacterial growth. Periodontal (gum) disease Colonies of bacteria and food debris residing under inflamed gums. Dental cavities and improperly fitted dental appliances May also contribute to bad breath. Dry mouth (Xerostomia) May be caused by certain medications, salivary gland problems, or continuous mouth breathing. Tobacco products Dry the mouth, causing bad breath. Dieting Certain chemicals called ketones are released in the breath as the body burns fat. Dehydration, hunger, and missed meals Drinking water and chewing food increases saliva flow and washes bacteria away. Certain medical conditions and illnesses Diabetes, liver and kidney problems, chronic sinus infections, bronchitis, and pneumonia are several conditions that may contribute to bad breath. Keeping a record of what you eat may help identify the cause of bad breath. Also, review your current medications, recent surgeries, or illnesses with you dentist.