Canker Sores: Treatments, Causes, And Symptoms

Canker sores are small, irritating ulcers that appear inside your mouth. They can be quite painful and may make talking or eating uncomfortable. Fortunately, it is possible to treat them effectively with the right measures. This article will give you an overview of canker sores, including what causes them, and how to treat them.

12 min readCanker Sores: Treatments, Causes, and Symptoms

Millions of people get canker sores at least a few times per year, and some people get them much more frequently. Although they are harmless, they are also distracting, annoying, and sometimes painful.

So, what can you do about them?

In this article, you will learn what causes canker sores, how to treat them, and how to prevent them from happening.

What Are Canker Sores? A Quick Look

Canker sores—also called aphthous ulcers—are tiny sores that appear inside the mouth. They are generally round or oval shaped and have a white, yellow, or gray center surrounded by a ring of red inflammation. They can range in size from a few millimeters to several centimeters and may be painful.

Depending on where they appear, they may show up as an ulcer on your tongue, a bump on your gums, or a sore spot inside your cheek.

About one in five people get them on a regular basis and they usually show up between the ages of 10 and 20.

Symptoms Of Canker Sores

The most common symptom of canker sores is pain, but there are a few other signs to look out for. These include:

A Burning Sensation In Your Mouth

One of the most common side effects of canker sores is the feeling of burning in the area your sore is located. Depending on the level of sensitivity in the specific area, this sensation can be mild or severe.

For example, a sore in the back of your mouth by your molars might cause burning or pain whenever you bite down or chew food. Conversely, a sore in the center of your cheek or lower lip might be far away enough from your teeth that you don’t feel any pain.

Swelling Around The Affected Area

Swelling is also typical with canker sores—not just with the large ones but also the smaller ones. The swelling is usually localized around the affected area and may cause pain if you press on it.

While you have a canker sore, you can also exacerbate the pain and swelling by drinking acidic drinks such as orange juice, or eating spicy foods. You may also accidentally bite the area, worsening the pain.

Difficulty Eating Or Drinking

Canker sores can be painful and uncomfortable, making it difficult to eat or drink some things. This includes both hard and soft foods, as well as hot or cold drinks.

Crunchy foods like chips and popcorn, as well as acidic drinks like soda or lemonade, can make the pain worse. Spicy foods like wasabi or peppers can also be too painful to eat.

White Or Yellow Center With A Red Border

Canker sores have a distinctive look associated with them, which includes a white or yellow center surrounded by a bright red border.

If you notice this, the good news is that you don't have a more serious condition to worry about. All you have to do is wait for the pain and other symptoms to subside.

Numbness In Your Mouth (In Severe Cases)

In rare cases, a canker sore may be so large and severe that it causes numbness in your mouth. This can make it difficult to eat or drink, as well as speak clearly.

This symptom is only found with major canker sores larger than a half-inch in diameter.

Types Of Canker Sores

There are three main types of canker sores: minor, major, and herpetiform.

Minor Canker Sores

Out of all types of canker sores, the most widespread are minor ones—they constitute around 80% of cases. These typically measure somewhere between 1/3 inch and 1/2 inch in size, and also go by the term "simple canker sores."

Although uncomfortable, minor canker sores are typically completely healed in two weeks or less. They may pop up out of the blue due to mouth trauma or lifestyle factors like stress, anxiety, or lack of sleep.

Major Canker Sores

Major canker sores that measure more than 1/2 inch are often stubborn, taking much longer to go away. Unlike minor canker sores, which have a round shape, major ones usually have an irregular border or mouth rash, making them stand out even further. Rarely but possibly, this type of sore may also leave a permanent scar.

Immune-compromised people, like those undergoing chemotherapy or with HIV, are more prone to developing major canker sores. These large sores make up roughly 15% of all mouth ulcers.

Herpetiform Canker Sores

This type of canker sore is much less common, accounting for only 5% of cases. It’s characterized by a cluster of many small mouth ulcers that measure no larger than 1/5 inch in diameter and look like blisters. These sores are often painful and may cause burning or tingling sensations in the affected area.

These sores get their name from the Greek word "herpes," which is a type of virus, but their symptoms and treatment are not related to it.

Canker Sores Vs. Cold Sores

Cold sores are another type of mouth ulcer that can be confused with canker sores, but they differ significantly.

Cold sores are physical symptoms of the herpes simplex virus (HSV-1 and HSV-2), appearing on the outside of your lips, cheeks, or chin. They don't often appear inside your mouth like canker sores, and they tend to last longer—typically up to two weeks.

Unlike canker sores, cold sores are highly contagious and can be transferred through skin contact. They also look different than canker sores—cold sores are yellow-grey pus-filled blisters, while canker sores are usually just red bumps or patches.

Canker Sores Vs. Ulcers

Canker sores are small ulcers, but other conditions, such as acid reflux and gastritis, can cause different kinds of ulcers.

These ulcers will appear differently than canker sores—they may be large and jagged with a yellowish tinge to them. They can also grow deeper and sometimes require medical attention.

Ulcers may also indicate a more serious medical condition, like mouth cancer. Canker sores don't typically cause any of these symptoms, and are usually much smaller.

Causes Of Canker Sores

It is still unknown why some people get canker sores while others don't. Still, there are several potential factors that can aggravate the condition:

Stress And Mental Health Conditions

Stress and oral health have been linked in numerous studies. Stress is proven to weaken the immune system, making it easier for mouth ulcers and other infections to take hold.

Other mental health issues like anxiety and depression have also been linked to oral health problems, including canker sores.

In addition to directly impacting the immune system, these conditions can also lead to behaviors that make it easier for sores to form. For example, anxiety may cause you to grind your teeth or bite your lip without realizing it.

It can also result in forgoing oral hygiene habits like brushing and flossing, allowing bacteria to build up in the mouth.

Hormonal Fluctuation

Canker sores are more likely to form during times of hormonal change, such as puberty, menstruation, and pregnancy. Hormones affect the natural balance of the body, which can in turn create an environment that favors mouth ulcer development.

The first time children go through hormonal fluctuations like puberty and menstruation is around the same age that canker sores begin to appear.

Although this isn't the only cause, there is a connection between the two.

Food Allergies

Allergies to foods like dairy, nuts, and chocolate play a role in causing canker sores. Common symptoms of food allergies include swelling, spots on your mouth, and difficulty breathing.

Typically, you will know the food responsible if it is caused by an allergic reaction. Blood or skin allergy tests can help you identify other potential triggers fairly quickly.

Menstrual Cycle

Hormonal changes that occur during your menstrual cycle can cause a flare-up of existing canker sores or even new ones. Women who suffer from regular outbreaks around their periods may find relief in taking an anti-inflammatory medication like ibuprofen to limit the pain and speed up healing.

Pregnancy also impacts oral health, and canker sores are one of the most common side effects.

Vitamin Or Mineral Deficiency

A deficiency in vitamins or minerals like vitamin B12, iron, riboflavin, and zinc is common in people with celiac disease or Crohn's disease. Vegans and vegetarians are also at an increased risk for these deficiencies since most natural sources of these vitamins and minerals come from animal products.

When someone is deficient in these vital nutrients, it reflects in their mouth in a few different ways. Purple tongue due to circulation problems, chronic dry mouth (xerostomia), and canker sores are just some of the problems.

Immune System Problems

Autoimmune diseases such as lupus, Crohn’s, or celiac cause your body to attack its own tissues, resulting in increased inflammation throughout. And since they pit the immune system against itself, the body can't properly fight off infections.

Canker sores are sometimes the result of increased bacterial buildup in the mouth and limited ability to fight off the infection.

Mouth Trauma Due To Injury Or Dental Work

Dental work is extremely stressful on your mouth. New braces, cleanings, or fillings can all cause ulcers to form in the mouth.

Accidental injury from biting your lip, cheek, or tongue can also be a trigger for canker sores. If these small cuts become infected after the trauma, an ulcer may form in its place.

Home Remedies For Canker Sores

Before taking a trip to your dentist's office or drug store, there's a good chance you can treat your canker sores from the comfort of your own home.


Antibacterial mouthwash is a great way to reduce the bacteria that can contribute to canker sore formation. If you choose one with fluoride, it can also help prevent cavities and gum disease.

When looking for a mouthwash to try, avoid any product with alcohol—the burn from the alcohol will only irritate your sore and prolong the healing process.

Saltwater Rinse

A homemade rinse with warm salt water is beneficial for a few reasons:

  • Reduces bacteria in your mouth
  • Increases the pH, lowering acidity levels
  • Helps to reduce inflammation
  • Relieves pain

To make a salt water rinse all you need to do is mix one-half teaspoon of table salt into a cup of warm water. Swish the mixture around your mouth for 30 seconds before spitting it out.

Aloe Vera Gel

Aloe vera is a home remedy for oral lichen planus (a disease that impacts the mucous membrane in the mouth) and can also provide relief for mouth sores, including canker sores.

Simply apply a small amount of aloe vera gel directly to your sore or ulcer with a Q-tip or cotton swab.

Nutritional Supplements

If you suffer from a nutrient deficiency due to dietary restrictions or personal choices, supplementing with extra vitamins and minerals can improve your health and lower your risk of sores.

Vitamin B12, iron, riboflavin (B2), and zinc are all important for proper oral health. If you are deficient in one (or more) of these nutrients, you can find supplements for each at just about any grocery or drug store.

Medications For Canker Sores

If you don't find relief from home remedies, there are several over-the-counter topical medications available that can help reduce the pain and irritation associated with canker sores.

Topical Medications

Topical solutions such as benzocaine (Anbesol) and dyclonine hydrochloride (Canker-Rid) provide a numbing sensation to the affected area, reducing pain.

For more serious canker sores or cases that don't respond to other treatments, there are also steroid medications available. These creams are applied to the sore directly and can help reduce inflammation, irritation, and pain.


Aphthasol is a prescription-grade oral paste that contains the active ingredient amlexanox, an anti-inflammatory agent which helps reduce inflammation and pain associated with the sores. The gel also helps promote healing by reducing bacteria growth in the mouth.

Aphthasol should be applied directly to canker sore lesions four times each day for 3-5 days, depending on the severity of your symptoms.

Oral Medications

If you have a severe canker sore or one that simply won't go away, there are also several oral medications available. These include colchicine, which is used to treat gout and helps reduce inflammation and pain caused by canker sores.

If your condition does not improve with other treatments, corticosteroids may be prescribed. These medications work by suppressing the body's immune response to reduce inflammation and irritation associated with canker sores.


Cautery is a medical procedure that involves burning tissue in order to stop bleeding, remove growths such as warts or tumors, or seal off blood vessels. It can be done through the application of heat (thermal cautery) or certain chemicals (chemical cautery).

Thermal cautery uses an electric current, heated metal instrument, or laser to burn away the affected tissue. Chemical cautery utilizes acids such as silver nitrate or trichloroacetic acid to cauterize the canker sore.

Cautery is effective for canker sores that are large or have become infected, although it is rarely needed. It helps to stop bleeding and promote healing by sealing off the affected area.

Complications Of Canker Sores

If you have a canker sore, you're unlikely to have any problems beyond the regular side effects. Still, complications such as the following are possible:

  • Increased pain and swelling that won't go away
  • Permanent damage or scarring to mouth tissues
  • Secondary infection in the mouth area
  • Appearance of additional canker sores before healing

If you experience any of these complications, or if your sore isn't getting better with treatment, contact your doctor for a closer look.

Prevention Tips For Canker Sores

Of course, preventing canker sores is always better than trying to treat them. Here are a few tips for reducing your risk of developing these painful sores:

  • Maintain good oral hygiene by brushing and flossing regularly.
  • Avoid foods that irritate the mouth, such as citrus fruits, spicy or acidic foods, and crunchy snacks.
  • Take a multivitamin and/or supplement your diet with foods that are high in vitamin B-12, zinc, iron, and folic acid.
  • Find ways to manage your stress from work, school, or home life.
  • Avoid biting the inside of your cheek or tongue.
  • If you smoke, consider quitting to reduce your risk of developing canker sores.

Want to learn more? These are the questions our customers ask us the most.

Are Canker Sores STIs?

Unlike cold sores, canker sores aren't STIs and can't be spread through kissing or sexual contact. Although some canker sores (herpetiform sores) share a similar name and characteristics as cold sore outbreaks, they have nothing to do with cold sores, which are caused by the herpes simplex virus.

Who Gets Canker Sores?

Why some people get canker sores and others don't remains unknown, but there are certain factors that increase the risk of developing canker sores.

People who have allergies, deficiencies in vitamins and minerals, or a weakened immune system may be more prone to these types of sores. Emotional stress, recent oral surgery, and underlying medical conditions can also contribute to the development of canker sores.

Are Canker Sores Contagious?

Canker sores aren't contagious and can't be spread through direct contact with an infected person. Still, if you have an active canker sore, you should practice good oral hygiene and take care to avoid spreading the bacteria or virus to other areas of your mouth.

How Do You Heal A Canker Sore Quickly?

There is no surefire way to make a canker sore heal quickly, but there are several things you can do to reduce the pain and help speed up the healing process:

  • Use topical medications such as benzocaine and lidocaine ointments.
  • Apply cold compresses or ice directly to the sore.
  • Rinse your mouth with warm salt water.
  • Avoid spicy or acidic foods, which can irritate the sore.
  • Brush your teeth gently and floss regularly.
  • Take an over-the-counter pain reliever if needed.

How Long Do Canker Sores Last?

Most canker sores will heal within 10 to 14 days with proper treatment. However, some may take up to a month or more to fully disappear. If your sore doesn't seem to be improving after two weeks, you might have to contact your doctor for further evaluation and treatment.

Can I Prevent Canker Sores?

To some extent, canker sores are random and unpreventable. But there are steps you can take to reduce the risk of developing them, such as maintaining good oral hygiene, eating a healthy diet, managing stress levels, and taking vitamins or supplements.

What Can I Expect If I have A Canker Sore?

Treatment for canker sores is straightforward. All you have to do is keep the area clean, use topical medications to reduce pain, rinse your mouth with warm salt water, and try not to irritate it. Additional measures like dietary changes and stress reduction can help as well.

When Should I See My Healthcare Provider About A Canker Sore?

It is rare that people need to see a healthcare professional about a canker sore, but some reasons to do so include:

  • Secondary infection
  • Multiple canker sores at once
  • Sores that worsen or don't go away
  • Additional symptoms like fever or lymph node swelling

How Do Canker Sores Form?

It is still unknown what causes canker sores, but some theories suggest that bacteria and viruses, allergies, or nutritional deficiencies could be the cause.

Other factors like emotional stress, physical trauma (such as a dental procedure), or foods with high levels of acidity may also trigger their development.

Is Putting Toothpaste On A Canker Sore Good?

Toothpaste does contain some soothing and antiseptic properties. Fluoride toothpaste is also an essential part of a good oral health routine. But if you’re using toothpaste to treat a canker sore, be careful not to use too much and make sure it doesn't contain any abrasive ingredients that could further irritate the area.

What Drinks Help Canker Sores?

Clean, pure water is the best thing to drink if you have a canker sore. But certain types of drinks, such as green tea, chamomile tea, and apple cider vinegar diluted in water may also help reduce inflammation and pain. Additionally, warm salt water rinses can also be beneficial for relieving the pain from your canker sore.

Should I Worry About Canker Sores?

Generally, canker sores are nothing to worry about. Most of the time, they are harmless and will go away on their own. However, if your canker sore persists or is accompanied by other symptoms, it’s important to visit your doctor for further evaluation and treatment.

Are Canker Sores Viruses?

Contrary to what many believe, canker sores are not caused by bacteria or viruses and cannot be transmitted from person to person. Unlike cold sores—which are the result of HSV-1 or HAV-2—canker sores represent just a small ulcer in the innermost layer of your mouth's lining.

What Happens If You Don't Treat A Canker Sore?

Canker sores go away on their own without treatment, but it may take up to a month or more. However, if you do not practice good oral hygiene and reduce irritating behaviors, the sores may become infected and worsen. That’s why it is important to properly care for your canker sore until it has healed.

Does Mouthwash Help Canker Sores?

Some mouthwashes can provide a little aid in healing a canker sore. However, many contain alcohol and other ingredients that may further irritate the area and worsen symptoms. So when choosing a mouthwash, make sure to select an alcohol-free one with antibacterial ingredients.

Does Salt Help Canker Sores?

Salt water is the best home solution for providing temporary relief from canker sores. Simply dissolve 1 teaspoon of salt in a cup of warm water and rinse your mouth with it several times a day. The salt helps reduce inflammation, neutralizes acids in the wound, and kills bacteria that could worsen the sore.

Do Dentists Care About Canker Sores?

Your dentist will only care about canker sores if they become infected or worsen significantly. Since this is so rare, most dentists won't bat an eye at a canker sore, even if it's in their line of vision. If you have any concerns or think you may need help with your canker sore, you can still bring it up during a dental visit.

What Is The Best Canker Sore Medicine?

The best canker sore medicine depends on the severity of your condition. Over-the-counter medications like topical gels, mouthwashes, and pastes may help reduce pain and inflammation. In more severe cases, stronger medications or prescription creams may be needed for relief.

Does Ice Cream Help Canker Sores?

Soft, bland foods like ice cream and yogurt can help reduce the pain of a canker sore. Additionally, cold items like popsicles or slushies may also help numb the area and reduce inflammation. However, these should only be eaten in moderation, as they aren't particularly healthy (and their high sugar content can be bad for your teeth).

How Do I Know If A Canker Sore Is Healing?

If your canker sore is healing, you may notice that it looks smaller and the pain or irritation has decreased. You may also experience a feeling of tightness around the area as the skin starts to heal. In addition, if your canker sore has scabbed over, it should be completely healed shortly after the scab falls off.