Bad breath is typically caused by poor dental hygiene, gum disease as well as from a variety of sources including throat infection, improper diet, heavy metal buildup,  indigestion, inadequate protein digestion, liver malfunction, postnasal drip, stress, or imbalance of normal flora in the colon.  Halitosis is therefore a symptom and not a disease.

Here are some basic tips:
- Brush your teeth and tongue after every meal.
- Replace your toothbrush every month to prevent bacteria buildup.
- Use dental floss.  Keep your toothbrush clean. Store it in a hydrogen peroxide solution to kill germs.

Bad breath normally signifies an underlying health problem, so a check-up with your physician is recommended if the above does not improve the condition.