Bad breath, or halitosis, is primarily caused by poor oral hygiene, but can also can be caused by retained food particles, gum disease, drainage from sinus dripping or systemic, respiratory or gastrointestinal problems. Proper brushing including brushing the tongue, cheeks, and the roof of the mouth will remove bacteria and food particles. Flossing removes accumulated bacteria, plaque and food that may be trapped between teeth. Mouth rinses are effective in temporary relief of bad breath. Consult your dentist and/or physician if the condition persists.