Alcohol and Bad Breath

The relationship between alcohol and bad breath is one of contradictions. On the one hand, we are told that drinking alcohol can cause bad breath, while at the same time, a number of commercial mouthwashes and rinses sold for the treatment of halitosis contain alcohol as an antibacterial ingredient. To deepen the confusion, scientific evidence backs up both claims: consuming alcohol can contribute to bad breath; adding it to mouthwash can have a demonstrably beneficial effect. How do we explain the contradiction?

Part of the explanation is that alcohol is a drying agent; drying agents and bad breath go hand in hand, because drying agents - alcohol, tobacco, and some drugs - cause saliva to evaporate and may even cause a decrease in the flow of saliva through the mouth. This is a bad thing for breath because saliva not only continually flushes and cleans the mouth, it also contains antibodies and antiseptic substances, which fight off organisms that can cause infection or produce offensive odors. People who suffer from a dry mouth often have halitosis too, whereas people with a healthy flow of saliva are less likely to develop bad breath. In social situations, many people notice that they have a dry mouth when they have consumed alcohol and bad breath goes along with that scenario, if only temporarily.

Research confirms the connection between drying agents and bad breath. Studies have shown that as saliva dries in the mouth, increasing amounts of volatile sulfur compounds (VSC) are released and expelled, causing worsening bad breath. This also at least partially explains the phenomenon of "morning breath," because saliva flow is decreased during sleep and the mouth is often dry upon waking. With alcohol and bad breath, the situation is often made worse by the addition of tobacco and food odors, which can be drying agents and sources of short term halitosis in their own right.

Other research paints a different picture of drying agents and bad breath: saliva also contains bacteria, and lots of sugars and proteins that the bacteria can break down, producing VSC. Experiments with saliva have shown that it breaks down and produces putrid odors if left to sit (another good reason to keep it flowing through at a healthy pace). The bacteria in saliva, in other words, can be source of halitosis. Alcohol is antibacterial and antiseptic, which explains the other side of alcohol and bad breath: alcohol kills bacteria that come in contact with it, so alcohol added to mouthwash does indeed tend to bring about an improvement in breath odor.

Clearly, combining alcohol and bad breath products can be effective, at least in the short term, but it comes at a price. Perhaps it's a price we don't need to pay: there are other effective products for fighting halitosis that don't have the unfavorable side effect of causing it as well.