Understanding and Treating Canker Sores

Canker sores, also known as aphthous ulcers, are small, painful lesions that develop on the soft tissues inside your mouth or at the base of your gums. Unlike cold sores, canker sores do not occur on the surface of your lips and they are not contagious. While they usually heal on their own within one to two weeks, the pain and discomfort they cause can be quite bothersome. Here’s a comprehensive guide on understanding, preventing, and treating canker sores.

What Are Canker Sores?

Canker sores are small, shallow ulcers that appear in the mouth and often make eating and talking uncomfortable. They can occur on the inside of the lips, cheeks, at the base of the gums, or on the soft palate. Canker sores are round or oval with a white or yellow center and a red border.

Causes of Canker Sores

The exact cause of canker sores is unknown, but several factors can trigger their development:

  • Injury: Minor injuries from dental work, aggressive tooth brushing, or accidental cheek bites.
  • Food Sensitivities: Particularly to acidic foods like citrus fruits, tomatoes, and certain spices.
  • Stress: Emotional stress can play a role in the development of canker sores.
  • Nutritional Deficiencies: Lack of essential nutrients like vitamin B12, zinc, folate, and iron.
  • Hormonal Changes: Hormonal fluctuations, especially in women, can trigger canker sores.
  • Medical Conditions: Certain conditions like celiac disease, Crohn’s disease, and immune system issues.
  • Genetics: A family history of canker sores may increase your risk.

Symptoms of Canker Sores

Common symptoms include:

  • A painful sore or sores inside your mouth.
  • A tingling or burning sensation before the sores appear.
  • Sores that are round, white, or yellow with a red edge.
  • Difficulty eating, drinking, or talking due to pain.

Treatment and Remedies

While canker sores typically heal on their own, there are several treatments and remedies to reduce pain and speed up healing:

1. Over-the-Counter Medications

  • Topical Pastes: Apply directly to the sore to relieve pain and protect the area. Common options include benzocaine (Anbesol) and hydrogen peroxide (Orajel).
  • Oral Rinses: Mouthwashes containing dexamethasone or lidocaine can help reduce pain and inflammation.

2. Home Remedies

  • Salt Water Rinse: Dissolve a teaspoon of salt in a cup of warm water and rinse your mouth several times a day.
  • Baking Soda Rinse: Mix a teaspoon of baking soda in a half cup of water and use as a mouth rinse.
  • Hydrogen Peroxide: Mix equal parts hydrogen peroxide and water, and apply with a cotton swab to the sore.
  • Honey: Apply honey directly to the sore. Honey has natural healing properties.

3. Avoid Trigger Foods

  • Stay away from acidic or spicy foods that can irritate the sore.
  • Avoid sharp, crunchy foods that can aggravate the sore.

4. Maintain Good Oral Hygiene

  • Use a soft-bristled toothbrush to prevent irritation.
  • Floss daily to remove food particles and bacteria.

5. Nutritional Supplements

  • If your diet is lacking, consider taking vitamin B12, zinc, folate, and iron supplements, but only after consulting with a healthcare provider.

When to See a Doctor

While most canker sores are harmless and resolve on their own, you should see a doctor or dentist if:

  • Sores are unusually large or particularly painful.
  • Sores persist for more than two weeks.
  • You have a high fever or feel generally unwell.
  • You experience difficulty eating or drinking.


Canker sores, though painful, are typically harmless and can be managed with a combination of home remedies, over-the-counter treatments, and lifestyle adjustments. By understanding the potential triggers and taking steps to prevent them, you can reduce the frequency and severity of canker sores and maintain better oral health.