Listerine

[Veramocor]

While rinsing my mouth I had a few interesting questions about my mouthwaah Listerine.

1. Is the high alcohol content responsible for killing the bacteria in your mouth or is it the other active ingredients it lists such as Thymol, Eucalyptol, Methyl salicilate (sp?), and menthol responsible for killing the bacteria?

2. Why is Listerine able to kill bacterial cells in your mouth but doesn't kill human cells such as the cells that make up your gums, tongue or mouth lining?

3. Finally Listerine doesn't kill every bacteria in your mouth. Why doesn't the natural selection pressures of Listerine cause bacteria to form which are reistant to it?

 

[Cawchy87]

Can't answer your questions, but I can tell you that bad breath is a result of chemical rections in your stomach rather than bacteria in your mouth as Listerine would love you to belive. Carbs cause the worst breath.

 

[TuxDave]

Originally posted by: Cawchy87
Can't answer your questions, but I can tell you that bad breath is a result of chemical rections in your stomach rather than bacteria in your mouth as Listerine would love you to belive. Carbs cause the worst breath.

But meats cause the worst farts...

 

[sao123]

1. Is the high alcohol content responsible for killing the bacteria in your mouth or is it the other active ingredients it lists such as Thymol, Eucalyptol, Methyl salicilate (sp?), and menthol responsible for killing the bacteria?

The Methyl Salicylate is the term for synthetic wintergreen oil.

Menthol is the chief constituent of peppermint oil and is responsible for its odor and taste and the "cooling sensation" when applied to the skin and mucosal surfaces.
(both of these active ingrediants are breath freshener)


Thymol is widely used as a general antiseptic. Due to its potent fungicide, bactericide and antioxidant properties thymol is applied primarily treatment of oral infections

Eucalyptus Oil is a powerful antiseptic. Ozone gas is produced when it is exposed to air.
(These two are the antisepics.)


The other main ingredients are water and alcohol. While alcohol may have some antiseptic properties, its primary reason for use here is as a solvent. Some of the active ingredients will dissolve into water, and some will not dissolve in water. However, the ones that do not dissilve in water will dissolve in alcohol. The Alcohol and water will mix readily without (the oil & water effect.) thus creating a super solvent for the rest of the ingredients.

2. Why is Listerine able to kill bacterial cells in your mouth but doesn't kill human cells such as the cells that make up your gums, tongue or mouth lining?

It can, will and does. Just at a much slower rate than it does the bacteria. Your mouth has a muscous membrane which slows cell exposure to chemicals in the mouth. The bacteria are not protected by this membrane, and they die quicker. Remember, you only gargle for 30 seconds. Try it for 20 minutes and plenty of your mouth cells will be dead.

3. Finally Listerine doesn't kill every bacteria in your mouth. Why doesn't the natural selection pressures of Listerine cause bacteria to form which are reistant to it?

I dont really know the answer to this.

 

[imported_KuJaX]

How do you prevent bad breath if it comes from the stomach? Aren't there over-the-counter pills of some sort?

 

[gururu]

that was a great response sao123.

Listerine contains 27% ethanol, which is antiseptic as well. alcohol is a desiccant, and it destroys cells by drying them out. That is in part why it burns after a good wash. some of the other additives like methyl salicylate help numb the effect so the burn isn't so bad. microbes, as far as we know, cannot develop resistance to the effects of alcohol at these and higher percentages. The main reason is that all organisms need water and well, alcohols render water useless. as far as the other antiseptics, I imagine that bugs can develop resistance to them since they are organic compounds. In fact I bet that there are fungi or bacteria that consume them in the wild (all organic products are biodegradable).

 

[Tiamat]

Excellent response sao123!

To follow up on this "natural selection" bit, from my knowledge, it could exist, however if it does, it would be rare. Most cells when givin these types of solutions explode very quickly do to huge diffusive or osmotic differences I believe.

I could be totally wrong, but I think that things like Salt water, IPA; they cause cells to rupture because of the water in the cell, exiting quickly trying to equilibriate the system. With Listerine, I think the result is similar. What you usually have to worry about is antibiotics. Bacteria can evolve immunities to antibiotics, and thrive in these environments. I dont think Listerine has antibiotics like the type you are prescribed by a doctor, so you might not have too much of this "natural selection/evolution of bacteria" going on.

Please correct me if Im totally off.

 

[unipidity]

Evolving resistence to an antiseptic is probably 'difficult'- without the evolutionary pressure driving the selection, the resistant population is probably rubbish in comparison to the originals. Since listerene is never going to kill 100% of the oral bacteria, and bacteria populations can rise so quickly, the pressure really is not at all strong. So the resistence is probably evolutionarily unfavourable.