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Mouth Ulcer

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Mouth ulcers or commonly called canker sores, are round or oval white lesions that develop on the inner surfaces of your lips and cheeks, tongue, palate (roof of your mouth), and gums. Canker sores are not contagious nor painful but can be serious in some cases. They are normally painless and can affect adults as well as children.

Canker sores are usually caused by viral infections or exposure to stress, hormonal changes, food allergies, or side effects of certain medications. Several autoimmune diseases have also been associated with ulcers in the mouth.


Canker sores usually have no specific symptoms. A tingling or burning sensation is often felt before one appears. This is followed by the formation of an ulcer, which usually lasts for about 7 to 10 days. Eventually, they heal on their own without any scarring. However, you may witness any of the following symptoms:

  • Burning sensation in your mouth
  • Swelling of the lip or tongue around the ulcer
  • Difficulty in swallowing because of ulcers on the gums, inside of the cheeks, or under the tongue
  • Dark spots of blood on the surface of the ulcer, which are visible only when it bursts open.
  • Ulcers which usually develop on the inside of your cheeks and gums, causing them to swell

Causes of Mouth Ulcers

Both infectious and non-infectious factors cause mouth ulcers. The commonly held belief is that infection, hence “non-contagious do not cause them.” However, bacterial infections such as Streptococcus can trigger them.

Some of the common causes of canker sores include:

Food allergies

Foods that cause allergic reactions in some people can bring about canker sores. These include nuts, fruits like cherries, strawberries, citrus fruits like oranges and grapefruit, chocolate and dairy products.

Foods high in oxalates

Oxalate is a chemical compound that can bring about inflammation of the mucous membranes in your mouth, leading to ulcers. Foods high in oxalates include peanuts, chocolate, spinach, parsley, and cocoa powder.

Stress, anxiety, and depression

Canker sores are seen to develop in individuals who suffer from stress or depression. Such instances can be triggered by tension at work or during school examinations.


Some women experience such ulcers during pregnancy, especially in the last trimester. This condition is known as Melkersson Rosenthal syndrome.

Food additives

Some food colorings and preservatives also bring about canker sores. They include sodium lauryl sulfate, benzoates, shellac glaze, and food dyes like tartrazine.

Physical irritants

Physical irritants include tobacco, alcohol, weather conditions like dryness and wind, certain tubes of toothpaste, and mouthwashes containing mint or citrus flavorings. You should check the label on the toothpaste before buying it to ensure that it does not contain any of these ingredients in high concentrations. The same applies when you are using mouthwash.

Mouth Ulcer Treatments

Antibiotics are not likely to work since an infection does not cause canker sores. However, there are several remedies you can try at home for fast healing.

  • Gargling with salt water is one of the most effective ways to heal ulcers in the mouth. It also reduces inflammation and pain associated with ulcers on the gums and mouth. A cup of water with ½ teaspoon of salt or baking soda should be mixed and then gargled several times during the day.
  • Avoid brushing your teeth; use an oral rinse instead to reduce the chances of eroding the ulcer when you brush your teeth.
  • Rinse your mouth with an antiseptic mouthwash to reduce the chances of bacterial infection. Avoid spicy foods that might irritate the ulcer further since they are already irritated. Anesthetics should also be avoided since they can further inflame the wound. These include nicotine, peppermint, and oral anesthetics like benzocaine or viscous lidocaine, which dentists usually prescribe.
  • Extracts of propolis can help heal canker sores faster when used as a mouthwash or gargle solution. It is important to note that while you are waiting for the canker sores to heal, you should avoid biting your lip and inside of the cheek since it might cause scarring.

Mouth Ulcer Prevention

You can prevent ulcers from developing by avoiding certain foods that have been identified to cause canker sores. It is advisable to check the label on your toothpaste and mouthwash before buying it. The same applies when using a mouth rinse since some of them contain known irritants. You should also avoid eating those foods that have been identified to cause the formation of canker sores in most people.

These foods include chocolate, peanuts, other nuts, dairy products like milk and ice cream, fruits with high sugar content like strawberries, cherries, and peaches. Beverages made from citrus fruits should also be avoided especially orange juice, since it contains a higher concentration of citric acid. If you have been diagnosed as having canker sores due to Melkersson Rosenthal Syndrome, consult with your physician to discuss the best way forward.

Canker sores are usually not treated but instead heal on their own without causing any complications. However, if you notice that the condition worsens over time, seek medical attention immediately.


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