The most common source of bad breath is your mouth. But there are other possible causes.
In the process of chewing and digesting food, debris can become trapped in the nooks and crevices of your mouth. If this debris isn't removed by thorough cleaning, it's broken down by bacteria creating an unpleasant smell.
The back of the tongue is a favourite place for odour-producing bacteria to live and it can be overlooked in your daily oral care routine. In addition, any nasal discharge dripping down the back of the throat coats the back of your tongue and feeds the bacteria living there.
Between the teeth and in the gum lines are other places food and bacteria tend to get trapped, then they rot and produce odours. This bacteria can lead to gum disease and tooth decay and one of the warning signs of gum disease is bad breath or a bad taste in your mouth.
Bad breath may be temporary. Some things that pass through your mouth can contribute to bad breath, but these are short-term problems; the odour lasting only until you next brush, floss or scrape. Eating foods such as garlic, onions and dairy products can produce temporary odours, while smoking and alcohol dry out the mouth and also cause unpleasant smells.