What to Do About Ulcers in the Mouth

Mouth ulcers, also known as oral ulcers, aphthous ulcers, or canker sores, are breaks in the tissue lining of your mouth, often along the base of the gums or inside the cheeks or lips, but can form in the floor of the mouth or on the tongue. (Very rarely a mouth ulcer may be the early sign of a cancer.)

They can be painful, annoying, and sometimes embarrassing, interfering with eating, drinking, brushing, and even talking. They are also very common. The pain from a mouth ulcer is caused because the nerves just below the surface of the lining of the mouth become exposed. Luckily most mouth ulcers are easy to treat.

Mouth ulcers are usually temporary, healing on their own within one to two weeks, and harmless (except for pain and inconvenience). If you get mouth ulcers that last longer than three weeks, or they recur regularly, you should seek medical attention as it may be a sign of a more serious problem.

Man with toothache at home
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The exact cause of oral ulcers is not known, but there are several factors that are suspected of contributing to their appearance.

  • Trauma or tissue damage: Damage to the mouth lining is common. Damage from vigorous brushing, orthodontic braces, ill-fitting dentures or biting the inside of your mouth can cause a mouth ulcer to form.
  • Infections: Bacterial, viral or fungal infections may cause mouth ulcers.
  • Stress-related mouth ulcers, aphthous ulcers: Most common in teens, stress-related mouth ulcers will heal within a couple of weeks. Prevention is by resolving stress-related problems or using stress-busting relaxation strategies. Hormonal changes and allergic reactions may also cause mouth ulcers.
  • Foods and drinks: Mouth ulcers may be triggered by acids in certain foods, including oranges, lemons, pineapples, strawberries, tomatoes, and others.
  • Toothpaste or oral rinses: Pastes or rinses that contain sodium lauryl sulfate may contribute to the appearance of mouth ulcers.
  • Vitamin deficiencies: A deficiency of vitamins such as B-12, iron, folate or zinc could also be a cause of mouth ulcers.

Disease-Related Mouth Ulcers

There are some serious causes of mouth ulcers. Mouth ulcers can be symptoms of herpes infection, sex-related infection, inflammatory bowel disease, leukoplakia, gingivostomatitis, oral cancer, oral thrush, celiac disease, and immune disorders.

If mouth ulcers are a symptom of a disease they are usually accompanied by other symptoms in the body, but not always. Most mouth ulcers last between one to two weeks. If mouth ulcers do not heal it could be a sign of disease that needs medical attention.

When to See a Healthcare Provider

If mouth ulcers do not heal within two to three weeks it could be a sign of disease that you need medical attention and treatment for. If mouth ulcers recur frequently, are large in size, continue to develop or are painless, see your healthcare provider for advice and a health check-up.


Some treatments will require the removal of the source of the mouth ulcer, such as the treatment of those caused by the disease.

For most mouth ulcers treatment is somewhat effective.

  • Pain relief creams or ointments such as Orajel or Anbesol
  • Rinsing the mouth with salt water and baking soda
  • Cooling mouth rinses with cold water or applying ice to the ulcer
  • Cool chamomile tea—swish it in your mouth and then swallow

Tips for Prevention

To prevent getting mouth ulcers, use these tactics:

  • Practice good oral hygiene.
  • Eat a healthy diet.
  • Employ gentle brushing for your teeth and gums
  • Get a good intake of vitamin B, C, and zinc
  • Avoid very hot drinks and food
  • Reduce stress

Frequently Asked Questions

  • Does COVID cause mouth ulcers?

    It can. COVID is well-known for causing people to lose their senses of taste and smell. It can also cause mouth ulcers in some people. It is unclear which variants are more likely to cause mouth ulcers.

  • How long will a mouth ulcer take to heal?

    Most mouth ulcers clear up on their own in about two weeks. See your health care provider if you have a mouth ulcer that does not heal after three weeks. 

  • How can you speed up healing of a mouth ulcer?

    To relieve the pain of a mouth ulcer, apply ice or a topical pain reliever like oral gel. Avoid abrasive, acidic, or spicy foods, and be careful while you chew or brush your teeth. 

    To speed up healing, apply a small amount of milk of magnesia to the sore a few times a day. Saltwater or baking soda rinses several times a day can also help to promote healing. 

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Cleveland Clinic. Canker sores.

  2. Hennessy BJ. Recurrent aphthous stomatitis. Merck Manual Professional Version.

  3. Erbaş GS, Botsali A, Erden N, Arı C, Taşkın B, Alper S, Vural S. COVID-19-related oral mucosa lesions among confirmed SARS-CoV-2 patients: a systematic review. Int J Dermatol. 2022;61(1):20-32. doi:10.1111/ijd.15889

By Jerry Kennard
 Jerry Kennard, PhD, is a psychologist and associate fellow of the British Psychological Society.