Canker Sores (Oral Aphthous Ulcer)

What is it? 

Canker sores are recurrent, non-infectious painful and open sores. They are also known as aphthous ulcer, aphthae, aphthous stomatitis and aphthosis. Some people are more prone to them than others including:

  • Women
  • Family members who also have/had canker sores
  • Under 40 years old
  • Weakened immune system
  • Those who have recently stopped smoking
  • Lacking in certain vitamins (vitamin B1, B2, B6, B12, folic acid, vitamin C) and minerals (iron, zinc, calcium) (weak link)
  • Taking certain medications (methotrexate, ibuprofen, etc)

There are three type of canker sores:

  1. Minor aphthae (the most common, consisting of ~80% of cases)
  2. Major aphthae (larger, more severe, of longer duration, and resolve with scarring, consisting of ~12% of cases)
  3. Herpetiform ulcers (cluster of pinpoint ulcers that may coalesce into irregular shaped lesions with possible scarring upon healing, consisting of ~8% of cases)

For the purposes of this article, we will be focusing on minor aphthae as they may be self-treated with over the counter medications. Referrals are needed for major aphthae and herpetiform ulcers.

What are common symptoms?

Symptoms of canker sores typically include one to 5 round or oval ulcers with a white, gray or yellow middle and raised red edges. They are painful and commonly located on the inside of cheeks or lips, side of the tongue, the soft palate or floor of the mouth.

They can be up to 1 cm in diameter and typically self resolve in 7 to 10 days with no scarring. They commonly start in childhood and can frequently recur, although they decrease in frequency and severity with aging. Oftentimes, burning and pain can precede the appearance of the canker sore by one to two days. 

What are common triggers?

  • Food, in particular: alcohol, almonds, carbonated beverages, cereals, cheese, chocolate, citrus, coffee, eggs, peanuts, strawberries, tomatoes
    • A strict diet eliminated of cow’s milk or gluten may resolve or improve recurrent canker sores for patients in those who are sensitive
  • Infections
  • Physical trauma (biting the tongue or inside of the cheek)
  • Stress and lack of sleep
  • Using toothpaste containing the detergent sodium lauryl sulfate (the foaming component of toothpaste)

What can be done to help prevent recurrences?

Avoiding triggers are important in minimizing the risk of recurrences. Use a toothpaste without sodium lauryl sulfate. Address sources of oral trauma (ill-fitting dentures or sharp/broken teeth). Maintain good oral hygiene which includes twice daily brushing and flossing and a professional dental cleaning at minimum of every 6 months.

Maintain a good diet and supplement with vitamins if deficient. Ensure adequate sleep and reduce stress.

When should I see my doctor or dentist?

Sometimes it is better to have your canker sore assessed by a doctor or dentist. Situations include:

  • If you have pain severe enough to affect eating 
  • If the ulcer is large (>1 cm in diameter), has been present for more than 14 days or if there are more than 5 ulcers present
  • If there are multiple clusters of ulcers that come together to form an irregularly shaped lesion
  • If you have a history of ulcers lasting longer than two weeks, heal with scarring and recur 6 to 12 times per year
  • Fever, joint pain or sores on other surfaces such as the skin, eye or genitalia
  • Red, white patches in the mouth especially if they are painful, swollen or bleeding
  • Ulcers on the hard palate (roof of the mouth) or gums
  • First occurrence later in life (> 30 years old)
  • Have a weakened immune system (HIV, etc), inflammatory bowel disease, Behcet syndrome, Reiter syndrome, celiac disease or lupus erythematosus
  • Blister-like lesions on hands or feet
  • Presenting with periodic fever, sore throat and swollen lymph nodes

They will assess your condition and severity, treat underlying conditions, or provide prescription therapies that will provide relief and benefit beyond what is available over the counter.

What can I do for self-treatment?

Canker sores (minor aphthae) typically self-resolve and there is no cure. The main goal is to lessen pain and discomfort while promoting healing.

The American Academy of Oral Medicine recommends topical agents as first-line therapy. Protective pastes can form a barrier over the sore (such as Orabase Paste). Local anesthetics (such as lidocaine or benzocaine) can help numb the area (such as Orajel) but only last for 20-45 minutes.

Combination products that combine an anesthetic in a vehicle that forms a protective barrier (such as Zilactin-B, Orabase with benzocaine, Kanka) may be the best of both worlds. Gels (have high alcohol content and can cause stinging or burning on application), ointments and pastes can be applied with a cotton-tipped swab 4 times daily (before meals and at bedtime) for up to 1 week.

It is recommended to dry the affected area prior to application and to avoid eating, drinking, or speaking for 30 minutes after each application.

If you are deficient in certain vitamins and minerals (as mentioned above), supplementation may help. Treatment with sublingual cyanocobalamin (vitamin b12) 1000mcg daily for 6 months may shorten the duration, reduce frequency and decrease pain even in patients not deficient in vitamin B12.

Milk of Magnesia and diphenhydramine (Benadryl) allergy liquid mixed in equal amounts may help relieve pain if one teaspoonful is swished in the mouth for about one minute and then spit out, every 4 to 6 hours as needed. Salt water rinses consisting of ½ to 1 teaspoonful of salt in one cup of warm water done several times a day especially after meals, may provide some symptomatic relief.

Pain relievers such as acetaminophen can be used; however, medications like NSAIDs (such as ibuprofen or naproxen) should ideally be avoided as these can cause canker sores and worsen lesions. 

Things to avoid while experiencing a canker sore involve using a softer toothbrush, and avoiding foods or beverages that are hard, crusty, sharp, spicy, salty and acidic as these may irritate and further increase pain. Unless prescribed or recommended by your doctor or dentist, it may not be ideal to use mouthwashes. Ensure adequate fluid intake to avoid dehydration. 

References available on page 2.