Bad breath, or halitosis, is primarily caused by poor oral hygiene, but can also 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 roof of the mouth will remove bacteria and food particles. Flossing removes accumulated bacteria, plaque, and food that may be trapped between the teeth. Mouth rinses are effective in temporary relief of bad breath. Consult your dentist and/or physician if the condition persists.