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Mouth ulcer

A mouth ulcer or canker sore is a painful open sore inside the mouth caused by a break in the mucous membrane. The condition is also called aphthous stomatitis.


Mouth ulcers often begin with a tingling or burning sensation at the site of the future sore. In a few days they often progress to form a red spot or bump, followed by an open ulcer.

The mouth ulcer appears as a yellow or grey oval with an inflamed red border and is on average about 3 mm across, but can be up to 1 cm across and occasionally larger. The grey, white, or yellow colored area within the red boundary is due to the formation of layers of fibrin. The ulcer, which itself is often extremely painful when agitated, may be accompanied by a painful swelling of the lymph nodes below the jaw, which can be mistaken for toothache.

Mouth ulcers may last anywhere from 1 to 4 weeks, with the greatest pain occuring at the onset of the ulcer.


The immediate cause of mouth ulcers is unknown, but factors that appear to provoke them include stress, illness, damage from rough teeth, hormonal changes, food allergies and deficiencies in vitamin B12 and folic acid. Consumption of particular foods, such as chocolate may also trigger mouth ulcers in some.

A common urban myth is that mouth ulcers are directly connected to the onset of the Herpes simplex virus, but in reality ulcers associated with herpes are of an entirely different nature from mouth ulcers. It is also said that excessive consumption of sweets is a cause of mouth ulcers - this is believed to be an old wives' tale. Other disorders can cause mouth ulcers, including oral thrush, leukoplakia, gingivostomatitis and oral lichen planus. Mouth ulcers are also associated with ulcerative colitis, Crohn's disease, coeliac disease (gluten sensitivity) and Behcet's disease. The treatment depends on the cause.

Home Treatment

Mouth ulcers normally heal without treatment within seven to ten days. The best start is to make sure you have good oral hygiene and avoid spicy/acidic/salty foods and drinks. In addition, one can treat the pain with several pain-relieving gels like Anbesol or Campho-Phenique available in drugstores. Some people claim that such gels also accelerate the healing of their sores.

Other home remedies vary in efficacy. Certain techiniques heal sores for some people, but there are no treatments with widespread medical support. Most seem to be based on an antiseptic (mild antibiotic), an antacid, or both. Antiseptic techniques suggested include the following:

  • Swab the sores with hydrogen peroxide
  • Rinse the mouth with an antiseptic mouthwash (e.g. Listerine)
  • Rinse the mouth with salt water-1 teaspoon of salt dissolved in 1 cup (250 ml) of warm water (aka. a saline solution)

Antacid techniques suggested include the following:

  • Swab the sores with milk of magnesia
  • Apply powdered alum directly to the sores-available in the spice aisle at your grocery store
  • Make a paste of baking soda and water-apply directly to the sores
  • Make a paste of crushed Tums and water-apply directly to the sores
  • Rinse the mouth with a baking soda-Water mix-1 teaspoon of baking soda dissolved in 1 cup (250 ml) of warm water
  • Rinse the mouth with warm milk

Combination therapies tell you to use the antiseptic first, and then the antacid. ie. Swab sores with hydrogen peroxide and then swab them with milk of magnesia.

Treatment for severe cases

Treatments based on antibiotics and steroids are reserved for severe cases, and should be used only under medical supervision. Tetracycline suspension is a common antibiotic prescribed for mouth ulcers. If the ulcer does not heal within a week, a doctor or dentists may cauterize it using a silver nitrate applicator or laser. This procedure immediately burns off the sore, causing it to completely disappear within a few hours or two to three days.

Some dentists recommend a sulfuric acid solution for treating mouth ulcers, such as debacterol.

The miracle cures that are advertised should be viewed with skepticism.


In some cases, switching toothpastes can prevent mouth ulcers from occurring, with some being able to reduce the occurrence of ulcers by approximately 80%. Sodium dodecyl sulfate (sometimes called sodium lauryl sulfate or simply SLS), a detergent found in most toothpastes, is thought to increase the incidence of mouth ulcers. Using toothpaste free of this compound has been found to help many people by reducing the amount and size of ulcers and in some cases, completely stopping them. A few individuals have noticed that switching to a toothpaste with Baking Soda prevented reoccurance of mouth ulcers. Many people have found that taking Lysine-L supplements can help to reduce the frequency of mouth ulcer appearances.