First, factor in the mouth itself, where there are cavities, many of plaque or tartar, tooth decay, or more severe tooth decay is left untreated. These teeth will become a den of germs and the rest of the food that can not be cleaned thoroughly and eventually rot. Consequently odor spread.
Second, factors from outside the mouth but still from the respiratory tract or disease or the public. Inflammation or disease in these parts of the same cause as the first factor. For example, tuberculosis (pulmonary tuberculosis) causes the mouth a little fishy smell, diabetes cause bad breath such as aceton (liquid nail polish).

Third, food or drink may leave the smell of the mouth for several hours afterward. For example, petai, coffee, liquor, etc..

Tips to prevent / deal with halitosis
Bad breath caused by various factors, so that we do not shunned by the people around us because the smell of the mouth, avoid or eliminate the cause of bad breath by:
- Check the condition of teeth and mouth to the doctor to find the causes of halitosis.
- Brushing teeth 2x a day after meals and at night before bed
- Avoid foods / drinks that smell stinging / sharp.