http://www.oramd.com/recedinggums/3-bleedingrecedinggums.htm The reason for this apparent paradox is the due to the fact that many of the bad breath products you see on shelves are formulated to kill the gram-negative anaerobic bacteria that cause halitosis but they also cause a very bad side effect: dry mouth. Chemicals such as alcohol are common in many of the bad breath products such as mouthwashes and rinses. Although very useful in reducing bacteria levels, they weaken the body's ability to keep the microbe levels low throughout the day.