Canker Sore (Aphthous Ulcer)

The formation of an aphthous ulcer thought to result from an allergic response (delayed hypersensitivity) to the mucopolysaccharide that is produced by bacteria while transitioning into mature forms.  It is also unknown why the onset of aphthous ulcer seems to correlate with some dental procedures and stress.

Characteristic of the aphthous ulcer is the repeated episodes of oval or round superficial ulcerations on the mucous membrane.  The common places are the inside of the lip, cheek, tongue, a floor of the mouth, soft palate, and sometimes the gums. Lesions are painful when contact with foods, especially acidic foods.  The size of the lesion ranges from 2 to 20 mm in diameter.

Aphthous ulcer begins with a small white, raised red papule on the mucosa.  Later, it expands and undergoes central necrosis to form an ulcer.  The disease is estimated to occur in 20% to 50% of the population.  The occurrence is more frequent in winter and spring and more prevalence in female than male.

The lesions are self-limiting and heal spontaneously within one to two weeks. However, recurrences are common. If symptoms persist for two weeks or more, or if you consistently have canker sores, you should consult with your physician. There may be underlying health conditions, e.g., food allergy, gluten intolerance, or vitamin B deficiency.

Other factors that trigger canker sore outbreaks are:
  1. Chemical irritant such as Sodium Lauryl Sulfate found in most toothpaste and mouthwash
  2. Physical trauma to soft tissue such as biting on the tongue or inside of the cheek, eating crispy snacks, rub the tongue against sharp edge tooth or chipped tooth, brush too hard with hard bristles
  3. Vitamin deficiency such as B-12
  4. Emotional stress
  5. Researchers found some foods may trigger a canker sore.  Example of triggered-foods is lemon, pineapples, oranges, strawberries, vinegar, milk, mustard and some grain cereals
  6. Systemic disease, e.g., Behcet's Syndrome, Ulcerative Colitis, Crohn disease


The lesions typically run a course of 1-2 weeks and resolve without treatment.  For several large and persistent canker sores, the symptoms can be controlled by using products or method mentioned on the list:
  • Prescription Drug:  Kenalog in Orabase (main ingredient: triamcinolone acetonide), topical paste to help accelerate the healing process

  • Prescription mouth rinse for difficult to reach areas, e.g., tonsils, soft palate and multi-lesions appear simultaneously in the mouth: Chlorhexidine Gluconate, e.g., Curasept mouthwash 0.2% twice daily. Curasept does not stain teeth.

    Chlorhexidine is an antimicrobial agent widely uses in:
    • Topical antiseptic
    • Cleansing wound, 
    • Skin cleanser before surgery
    • Mouth rinse after surgery
    • Periodontal treatment
    • Aphthous ulcer

  • Non-prescription drug: Canker-Rid®
    Apply Canker-Rid® fluid at the lesion as soon as the lesion appears will immediately relieve the symptoms (be careful not to drop the liquid outside the mouth as it can stain).  The main ingredient in Canker-Rid® is Propolis (propriety blend of bee products)

    Non-prescription mouth rinse:  Gly-Oxide Liquid Antiseptic Oral Cleanser, 2 Fluid Ounce contains carbamide peroxide that may bleach your teeth as well

  • Gengigel Gel uses to heal the trauma wound and arrest the aphthous ulcer:

    • Massage Gengigel to the traumatized gums, before the breakout into ulcer
    • Rinse with Gengigel mouth rinseafter the breakout 3-4 times daily

    Gengigel contains hyaluronic acid (Hyaluronan) that stimulates new production of healthy tissue, reduce inflammation, increase blood supply, and resist recurrence of infection

  • Taking a sub-lingual vitamin B12 tablet (1,000 mcg) each evening before bedtime can reduce the recurrence times of aphthous ulcer.

  • Laser light - Periolase®MVP-7™

Note: According to FDA, do not use Benzocaine topical products (gels or liquids) to numb the affected areas due to a severe and potentially fatal adverse effect from Methemoglobinemia.  Methemoglobinemia is a blood disorder in which an abnormal amount of methemoglobin (a type of hemoglobin that cannot release oxygen) occurs.

During the treatment; avoid eating sweet snacks, acidic fruits and fruit juice including wine.  At night, cover the sore with "Canker Cover" will help relieve pain and enhance healing. Whatever remedy you select, continue until the sore disappears. Most remedies will sting or burn for a short period.
    1. Avoid using toothpaste that contain Sodium Lauryl Sulfate
    2. Avoid acidic fruits (tomatoes, orange, grapefruit, etc.), fruit juice, and soda
    3. Avoid drinking chlorinated water (tap water)
    4. Keep a record of food you eat before having a canker sore. Avoid the food that you repeatedly consume before having a canker sore.
    5. Avoid spicy food
    6. Brush gently with soft toothbrush
    7. Use warm salt water (add a lot of salts) to rinse your mouth after biting on the inside of your cheek.
    8. Take some probiotic or yogurt
    9. Take vitamin B-12 daily
    Note: many people were mistaken aphthous ulcer to cold sores (Herpes).


    1. Great Post! It's very nice to read this info from someone that actually knows what they are talking about.
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    2. Some foods do trigger canker sores so it is definitely a good idea to pay attention to diet