I brush my teeth constantly but still have bad breath. What can I do?

Brushing and flossing are definitely the first steps to eliminating bad breath. Brushing and flossing remove bacteria responsible for creating odorous sulfur compounds and the food they feed on. However, bacteria hide not only on and around the teeth but also on the tongue under a layer of mucous. Here they are free to create odors. You might want to consider a tongue scraper. They're extremely effective at removing this protective mucous layer from the back of the tongue.

The latest products on the market for bad breath are toothpastes and mouthwashes containing chlorine dioxide. The chlorine dioxide neutralizes the odorous sulfur compounds, instead of simply covering up the odour.