Are Cavities Contagious?

Just like you can catch a common cold, it’s possible to also “catch a cavity.” It may come as a surprise, but cavities are in fact contagious. But don’t worry. We’ve got you covered with the ins and outs on how to avoid getting a cavity, and how to prevent passing it to others. 

What is a cavity?

Also known as “dental caries,” a cavity is a small hole that forms on your tooth from too much bacteria buildup. Teeth are very strong. But over time, bacteria can build up on and around your teeth and break down the enamel. This can leave you prone to developing a cavity. 

Cavities don’t just form from eating sugary foods. As we eat snacks or meals throughout the day, the leftover food particles are processed into acids by bacteria in your mouth. These acids get trapped against your teeth by a thin film called plaque. The buildup of plaque can cause cavities to form.

Cavities should get cleaned and filled to prevent them from spreading to other teeth or even other people.

What makes cavities contagious?

Cavities spread because of the bacteria that cause them. There are many different types of bacteria that can live in the mouth. But a certain bacteria called Streptococcus mutans (S. mutans) are the main cause of cavities.

You may be wondering about the effects of kissing on cavities. One small study showed that S. mutans can spread through saliva. That means, in theory, that kissing can transmit cavities. But don't worry, the environment in your mouth has to be just right for S. mutans and other types of bacteria to thrive. 

These bad bacteria are also very sticky. If you leave the plaque for too long on your teeth, the bacteria start to bond together and get harder to remove. These bacteria clusters can cause other teeth to be affected. Brushing and flossing your teeth regularly can help prevent the bacteria buildup that causes cavities to form.

How quickly do cavities spread?

The time it takes for cavities to form and spread will vary from person to person. It’s often based on your oral health as well as other environmental factors. It may seem like your cavities have popped up out of nowhere, but it can take a while for them to spread.

The longer you leave plaque on your teeth, the quicker a cavity may develop. If you already have a cavity, the environment in your mouth is perfect for bacteria to thrive. And this can cause your cavity to spread and other cavities to develop. 

What to do if you have a cavity?

If you’re having tooth pain and think you have a cavity, there are a few things you should keep in mind.

1. Schedule a dental appointment as soon as possible

Schedule an appointment with a dentist sooner than later. This is key to preventing the need for more involved and expensive treatment later on. 

A dentist will also be able to help you find better ways to clean your teeth. These instructions will decrease the spread of cavities to other teeth or other people.

2. Decrease the amount of snacking throughout the day

A lot of packaged snacks include a high amount of sugar and starch. Continuous snacking will add sugar and starch to the bacteria in your mouth. And this will form even more acids that break down your teeth. If you already have a cavity, then more acids can make things even worse.

3. Increase the amount of daily brushing and flossing

Keeping your teeth as clean as possible will decrease the chance of your cavity getting worse. If it’s small enough, your cavity may even become inactive if kept clean. 

In general, you should aim for brushing your teeth at least twice a day and flossing at least once each day. And for the best results, you may want to floss before you brush your teeth. Talk with your dentist about how often you should clean your teeth if you have a cavity. 

How long can cavities go untreated?

In some cases, cavities can take years to get to the point of needing treatment. But sometimes cavities can progress in a matter of months. This all depends on the health of your mouth.

The best advice to keep in mind is “the earlier the better.” Regular dental visits will help you know the status of your oral health. If you do have a cavity, getting it cleaned out and filled will save you money and keep you from extensive damage and pain. 

How do you prevent cavities?

Having good oral hygiene habits is the best way to prevent cavities. A few dental tips and tricks to help prevent tooth decay are: 

• Schedule a dental cleaning at least every 6 months.

• Rinse your mouth with antibacterial mouthwash after brushing.

• Brush your teeth twice a day with fluoride toothpaste and floss once a day.

• Avoid frequent snacking and sipping of sugary drinks.

• Consider a healthier diet that includes less sugary and starchy foods.

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Written by:

Zack Youngblood, DMD

Zack Youngblood, DMD, is a dentist who strives to change the general look of dentistry. Before stepping foot in the clinical field, he authored multiple works that helped dental students and dentists find their unique path in dentistry.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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