Does Listerine Kill Bacteria In Your Mouth?

In this blog post we are going to learn about the actions of Listerine mouthwash and about the various types of Listerine mouthwashes for different conditions.

Does Listerine Kill Bacteria In Your Mouth?

Yes, Listerine mouthwash kills bacteria in the mouth. Listerine mouthwash is antiseptic in nature and has antibacterial properties. When it is used regularly, it kills the germs in the mouth and also keeps the plaque and gingivitis causing bacteria under control. Listerine is one of the most commonly prescribed mouthwashes by dentists. It is quite popular for its anti-plaque activity.

According to the manufacturers of Listerine, it has antibacterial properties that can kill upto 99.9% of germs in the mouth. Researchers have noted that Listerine starts acting on the bacteria within 30 seconds of use and with continuous use, it brings down the bacterial count of the mouth significantly. Listerine is also very potent in controlling bad breath or halitosis and is great for people who suffer from bad breath.

Why Do We Have Bacteria In The Mouth?

Bacteria and other microorganisms are present all over our body and inside all organs as well. This does not mean that you will get a bacterial infection. Broadly, bacteria can be put into two groups, good bacteria and bad bacteria. Not all bacteria are bad and all bacteria will not cause diseases in the body. It is the bad bacteria which upon increasing in number, which cause diseases and infections.

It is important to have a balanced quantity of good bacteria in the body for us to stay healthy. Good bacteria is especially beneficial for our gut. They keep our digestive system in good condition and also help in digestion and absorption of nutrients. Even though bacteria have a generally bad reputation as disease causing organisms, it is important to remember that our body needs a balanced quantity of good bacteria also known as probiotics. Read this article to know more about probiotics.

Researchers have found over 500 species of bacteria in the human mouth. This plethora of bacterial species present in the mouth are linked with a number of oral diseases like gingivitis, periodontitis, dental plaque, teeth caries or cavities, bad breath etc.

So does this mean that because we have such a large number of bacteria in our mouth, all of us will develop some oral disease? No, this is not the case. A disease only infects the body when the body’s immunity lowers and when the count of the bad bacteria in our body increases tremendously. It is this increase in the number of bad bacteria in our body that invades our healthy organs and leads to diseases.

Bacteria are present on all the surfaces of our teeth and gums. Infact, our saliva is also full of many bacterial species. Therefore, co hosting bacteria and other microorganisms in the body does not mean that you will get sick. The healthy bacteria are important to maintain the healthy microflora in the body for proper functioning of the systems. That is why you need not worry about the fact that there are bacteria in your mouth.

What Does Listerine Do?

Listerine is an antiseptic mouthwash. The first and foremost action of listerine when you rinse your mouth with it, is to flush your mouth and clean all the food debris from every nook, corner and crevice in the mouth. Flushing the food remnants makes sure that once you are finished eating or drinking, there are no food particles stuck in the mouth on the teeth or between teeth or under the gums. This ensures a clean mouth and stops the bacteria from digesting any food particles which can cause cavities and gum diseases.

As listerine is an antiseptic agent, it kills the germs in the mouth. Research has shown that Listerine mouthwash has strong bactericidal or bacteria killing properties in it and it kills upto 99.9% of the germ count in the mouth and saliva. Even at a minimum concentration, Listerine has shown excellent bacterial growth inhibiting properties, making it one of the best mouthwashes for controlling oral plaque, calculus, cavities and gum diseases.

Another important action of listerine is to form a protective layer on the enamel. The sodium fluoride content in this antiseptic mouthwash forms a protective layer on the tooth and fights cavities for as long as 24 hours.

As it has germ killing properties, Listerine keeps bad breath in check too. It keeps the breath fresh all day long and fights halitosis or bad breath. Any person who suffers from morning breath or halitosis because of any reason should use Listerine and they will surely notice a difference in the breath with continuous use.

What are the ingredients of Listerine?

Listerine mouthwash has a combination of many ingredients, each of which work together to fight cavities, gum diseases, oral germs,plaque, calculus and bad breath. Let us have a look into each of the ingredients in Listerine mouthwash and their actions.

Listerine has water, alcohol, sorbitol, sucralose, sodium benzoate, benzoic acid, sodium saccharin, and poloxamer 407 in it. In addition to these ingredients, Listerine has four essential oils in it which set this formula apart from many other commercially available mouthwashes. 

These four essential oils are thymol, eucalyptol, menthol and methyl salicylate. 

Each of these ingredients have their own individual actions. Water  is used as the base of the mouthwash. Alcohol helps to dissolve the oils in the formula so that they can mix well with other ingredients. Also, being a disinfectant, alcohol also plays a role in killing the germs in your mouth. Sorbitol provides the sweet flavor to the mouthwash. It also acts as an hygrating agent in the formula. Similar to sorbitol, sucralose also acts as a flavoring agent and gives the mouthwash its sweet flavor. 

Benzoic acid is one of the main ingredients that fights the germs. It prevents the growth and spread of the microorganisms in the mouth. Along with its anti-germ properties, it also helps to adjust the pH of the mouthwash so that it does not harm the soft tissues of the mouth. Similarly, sodium benzoate too acts as a pH maintaining ingredient in the mouthwash.

Next, sodium saccharin is another flavor enhancing ingredient in the list. All these flavor enhancing ingredients together balance each other and impart the sweet flavor to the entire mouthwash. Poloxamer 407 is responsible for flushing out all the food particles that get stuck to the surfaces of teeth and between the teeth. Just like alcohol, this ingredient also helps in mixing all the oils together to form one potent blend of all these ingredients.

The four essential oils have many important roles to play too. Eucalyptol is usually derived from trees in Australia and it has strong anti microbial activity. It acts against both bacteria and fungal growths in the mouth. Menthol gives the fresh and cooling effect after rinsing with Listerine. It also has antibacterial properties in it. Thymol also has strong evidence that suggests its germ killing properties. The fourth essential oil, methyl salicylate, is commonly found in many chewing gums. It is known for its fresh flavor and bad breath fighting properties.

Frequently Asked Questions (Does Listerine Kill Bacteria In Your Mouth)

How do you kill bacteria in the mouth at home?

Brushing your teeth twice daily along with using a good mouthwash will keep your mouth free of disease causing bacteria. Brushing properly and rinsing your mouth after every meal in the day will make sure that the bacteria in the mouth do not grow and cause infections. Apart from this, rinsing with baking soda mixed with water helps to fight germs in the mouth too.

 However, if the bacteria in your mouth has already caused some kind of an infection like tooth cavity, abscess of gingivitis, simply brushing will not kill the bacteria. You need to visit a dentist and get proper dental treatment along with medicines for killing the disease causing bacteria.

Does bacteria grow in the mouth overnight?

Yes, bacterial overgrowth happens in the mouth overnight. When you are asleep, you do not swallow as you do when you are awake. This causes less secretion of saliva in the mouth. Less saliva makes a favorable environment for the bacteria to overgrow and thrive. This is why it is essential to brush your teeth before going to bed so that the food particles are removed and your teeth and gums are clean when you go to sleep.

How do I wake up with a clean mouth?

In order to wake up with a clean mouth in the morning, it is important to brush before going to sleep every night. Along with brushing, it is also equally necessary to use a good mouthwash after brushing. This will ensure that the bacteria does not overgrown in your mouth while you are asleep and you will wake up with a fresh and clean mouth in the morning. 

This habit will not only make sure that you wake up with a clean mouth, it will also reduce your chances of developing tooth cavities and gum diseases. In short, your teeth will remain healthy for a long period of time by practicing these simple oral hygiene methods.

Why does my mouth smell bad in the morning?

Bad breath in the morning after waking up is known as morning breath. If your morning breath is bad, it means that your mouth was not clean at night. When you are asleep and saliva production reduces, the bacteria overgrown and thrive on the leftover food particles stuck to the teeth. They start digesting these food particles and produce acids. This results in bad breath. The less prosecution of saliva during sleeping causes insufficient cleaning of the mouth, which leads to bad breath.

Why does my breath stink even after brushing?

Bad breath even after brushing can be due to multiple reasons. It can be due to improper brushing. When you do not brush your teeth thoroughly, the teeth do not get cleaned completely and this results in bad oral hygiene, causing bad breath. Another reason for bad breath eveN after brushing is not cleaning the tongue. When you do not clean the teeth, build up over the tongue over a long period of time can make the tongue quite dirty and it starts to smell bad.


Listerine is a potent mouthwash for killing germs in the mouth. It is important to use it regularly along with proper brushing to control the growth of microorganisms in the mouth and keep the teeth and gums free of diseases. Talk to your dentist if you want to know which will be the best mouthwash for you based upon the condition of your teeth.

Other FAQs about Mouthwash that you may be interested in.

Tooth Pain Goes Away With Mouthwash

Can Mouthwash Cause A Sore Throat?

Best mouthwash for sore throat


Was this helpful?

Thanks for your feedback!