1. Poor dental hygiene: If you don’t brush and floss often enough, bits of food will start to cause decay inside the mouth
2. Infections in the mouth: Periodontal (gum) disease, usually caused by plaque bacteria accumulation at the gum line.
3. Respiratory infections: Throat, sinus or lung infections can cause an accumulation of mucus in the throat
4. External agents: Garlic, onions, coffee, cigarette smoking, chewing tobacco, alcohol and some spices can all cause halitosis
5. Dry mouth (Xerostomia): Caused by salivary glands problems, medicines or mouth breathing.
6. Systemic illnesses: Diabetes, liver, kidney, lung, sinus and relfux diseases, renal infections and others
7. Psychiatric illness: Some people believe they have bad breath when they do not. This is called halitophobia.
The above information was sourced from Smile Magazine, Issue #4, 2009.