Canker Sore Causes and Treatments

What are Canker Sores?

Canker sores are interchangeably known as mouth ulcers, aphthous ulcers, recurrent aphthous stomatitis or oral ulcers. They plague the lives of millions of people all over the world. These small oral ulcers can make life unbearable when eating, drinking, speaking, or swallowing.

Canker Sores can occur anywhere inside the oral cavity, including the inner surface of the lips and cheeks, base of the gums, tongue and soft palate. There can be one or many canker sores at the same time. A canker sore is not a form of cancer, although squamous cell carcinoma may present itself as an ulcer that does not heal.

The first canker sores usually occur between the ages of 10 and 20. During life, episodes usually but not always, become less frequent and less severe. Interestingly, women often report increased susceptibility to canker sore formation during certain times of their menstrual cycle. Some women report complete relief from canker sores during pregnancy.

Interestingly, canker sores affect people to varying degrees of severity. Some people may get an occasional outbreak of canker sores once or twice a year while others may suffer near continuous overlapping episodes of canker sores.

Some common symptoms of canker sores are:

  • Painful red spot or bump that turns into an open ulcer.
  • Center of the ulcer is yellow or white.
  • Small in size, usually under 1 cm in diameter, but can be larger.

Some people, even doctors, confuse canker sores with "cold sores" which are also known as fever blisters. Both are painful, annoying and recurring but they are not the same thing.

The Differences between Canker Sores and Cold Sores

Canker Sores

Cold Sores

Only occur inside the mouth

Mostly on outside of mouth - sometimes on the inside of the mouth, but only on "hard" surfaces (palate)

Not Contagious


Not Viral (not caused by a virus)

Caused by Viruses

Caused by damage to oral tissue, often by sodium lauryl sulfate, a common foaming agent ingredient in almost all toothpastes

The first sign is appearance of small blisters (vesicles)

What Causes Canker Sores?

The Soap in Your Toothpaste - Sodium Lauryl Sulfate

The latest research shows that certain chemical compounds can trigger the production of canker sores. It may shock you to know, but among those chemical compounds is something that is commonly found in most toothpastes. It's SOAP. Yes, there is soap in most toothpastes!

For many years the major oral care manufacters have used soap, chemically known as sodium lauryl sulfate (SLS) to create a foaming action when you brush your teeth. The foam does not provide any benefits other than to fool you into thinking that there is a deep "cleansing" action taking place. The fact is, the foam does not get your mouth any cleaner.

However, the harshness of sodium lauryl sulfate does, in susceptible individuals, cause microscopic trauma or membrane disruption to the skin cells in the mouth. This along with trauma or actions of the immune system may lead to canker sore formation.

In a study at the University of Oslo in Oslo, Norway, Drs. Barvoll and Brokstad revealed a 60-70% reduction in the number of canker sores in patients who used SLS-free toothpaste during the three month test period. Additional studies have since shown equally promising results.

In the clinical studies, patients using SLS toothpaste displayed a greater amount of desquamation (loss of a layer of skin lining the inside of the mouth). This has led to the theory that SLS may contribute to RAS (canker sores) by causing injury to the oral epithelial cells (skin cells lining the inside of the mouth).

SLS, by denaturing protective mucus proteins, may also disrupt the protective layer of mucus which lines the inside of the mouth (a denatured protein is a protein which has lost its three dimensional shape thereby becoming nonfunctional and useless). The denaturing of mucus proteins makes the cells lining the mouth more susceptible to injury and canker sore formation.

Other Common Causes of Canker Sores

  • Allergies to food products and certain preservatives
  • Trauma from brushing your teeth too vigorously
  • Lip biting
  • Stress
  • Trauma from eating hard, rough foods (ex: potato chips, pretzels)
  • Deficiencies in vitamin B12, iron, and folic acid.

Current theories on the causes of canker sores have focused on the immune system. This research suggests that canker sores may be caused by the body's own immune system attacking the cells lining the inside of the mouth.

Canker Sore Treatments and Remedies

Canker sores usually heal on their own with the pain generally lasting 10 to 12 days. You have the option of doing nothing and tolerating the pain or using any number of over the counter treatments or home remedies to alleviate the pain.

Home Remedies and Treatments for Canker Sores.

  • A glass of warm salt water swirled around in your mouth may relieve pain.
  • A half-and-half mixture of hydrogen peroxide and Milk of Magnesia soothes a canker sore. Apply the mixture to the canker sore using a cotton swab three to four times a day.
  • Mix one half Benadryl to one half Milk of Magnesia and swish around your mouth for one minute or so. Afterwards, spit out the rinse. Do not swallow.

Over-The-Counter Treatments for Canker Sores.

  • Products intended for oral pain relief that contain benzocaine numb the canker sore, providing instant relief from the pain.
  • Aspirin, acetaminophen or ibuprofen can be used for pain relief.
  • Carbamide peroxide solutions release oxygen on contact with the ulcer. This action cleans the sore, offering pain relief as well as antibacterial properties.

Doctor Prescribed Treatments for Canker Sores

Medical intervention is required for canker sores that refuse to respond to time or over the counter remedies for relief. Your doctor can diagnose the issue and prescribe medication accordingly.

  • Silver nitrate provides fast relief and healing. Application should be done by a medical provider, but silver nitrate sticks are available on the Internet. There is a burnt taste associated with their use, but the canker sore on tongue pain goes away completely within a few hours and the sore heals within days.
  • Debacterol, a combination of sulfonated phenolic compounds and sulfuric acid, chemically burns the ulcer. It works in a similar manner to silver nitrate and is only available by prescription.
  • Various antibiotics and corticosteroids are available from the doctor for relief. All are used differently, but all provide quick pain relief and reduced healing time for severe canker sores on tongue.

Which Form of Canker Sore Relief is Right for You?

How you heal a canker sore depends on severity of the sore and pain tolerance. Having a canker sore on tongue causes difficulty in eating even the softest of foods, so getting rid of the canker sore quickly is key. You can start with home remedies and work on from there. It may be that you prefer to get aggressive and go for the strongest form of treatment in order to relieve the pain so you can resume normal eating functions quickly. Ultimately, there are plenty of options available to relieve the suffering of a canker sore on tongue quickly and easily.

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