What Causes Canker Sores?

The exact cause of most canker sores is unknown. Stress or tissue injury is thought to be the cause of simple canker sores. Certain foods – including citrus or acidic fruits and vegetables (such as lemons, oranges, pineapples, apples, figs, tomatoes, and strawberries) – can trigger a canker sore or make the problem worse. Sometimes a sharp tooth surface or dental appliance, such as braces or ill-fitting dentures, might also trigger canker sores.

Some cases of complex canker sores are caused by an underlying health condition, such as an impaired immune system; nutritional problems, such as vitamin B-12, zinc, folic acid, or iron deficiency; and gastrointestinal tract disease, such as Celiac disease and Crohn’s disease.

What Are the Symptoms of Canker Sores?

You may have a canker sore if you have:

• A painful sore or sores inside your mouth – on the tongue, soft palate (the back portion of the roof of your mouth), or inside your cheeks
• A tingling or burning sensation prior to the appearance of the sores
• Sores in your mouth that are round, white, or gray in color, with a red edge or border

In severe canker sore attacks, you may also experience:

• Fever
• Physical sluggishness
• Swollen lymph nodes

If sores are large, painful, or persistent, your dentist may prescribe an antimicrobial mouth rinse, a corticosteroid ointment, or a prescription or nonprescription solution to reduce the pain and irritation.

Can Canker Sores Be Prevented?

Although there is no cure for canker sores and they often reoccur, you may be able to reduce their frequency by:

1. Avoiding foods that irritate your mouth – including acidic or spicy foods

2. Avoiding irritation from gum chewing

3. Brushing with a soft-bristled brush after meals and flossing daily, which will keep your mouth free of foods that might trigger a sore.

You should call your dentist about canker sores if you have:

Unusually large sores

Sores that are spreading

Sores that last 3 weeks or longer

Intolerable pain despite avoiding trigger foods and taking over-the-counter pain medication

Difficulty drinking enough fluids

A high fever with the appearance of the canker sore(s)