Canker Sores! Ouch!

Canker sores (also called apthous ulcers) usually occur inside your mouth  and make eating and talking uncomfortable. Their root cause is unknown, but we do know several factors that can contribute to their formation.

  • Stress or injury to the mouth tissue:  Injury can be caused by something sharp cutting or abrading the gums, braces, or ill fitting appliances like dentures.
  • Acidic foods (citrus, tomatoes etc.)
  • A toothpaste or mouthwash ingredient, especially Sodium Lauryl Sulfate (SLS) which is a foaming agent.
  • Hormonal changes
  • A diet that does not have enough Vitamin B12

Most canker sores will heal on their own within two weeks even if you don’t do anything. Some people will use pain-relieving products like Ora-Gel to reduce the discomfort. Large or persistent canker sores might require a prescription from your dentist or doctor.

If you are prone to canker sores, here are some things you can do to try to prevent outbreaks:

  • Get more sleep! Stress weakens the immune system so it can’t fight off problems in your body, including your mouth.
  • Avoid foods that trigger them . If you can’t avoid them, brush with a soft bristle tooth brush after having them to minimize their effect.
  • Switch to oral care products that don’t contain SLS.

Other ways to reduce the pain of canker sores while you have them are:

  • Some people have reported relief from alum powder purchased from drug store or styptic pencils (also used to stop bleeding from shaving cuts).  A note of trivia: alum is also the compound added to mouth puckering gum found at joke shops.
  • Others recommend Propolis extract—place a drop directly on the canker sore and allow to dry. It’s very sticky and messy; tar-like and unsightly; and hard to remove. It seems to work best if placed when the canker sore is first forming.
  • Others recommend a mouthwash made from deglycyrrhinzinated licorice (DGL). Find the DGL and mix 200mg DGL with 200 ml water. Rinse 4x/day and don’t drink after rinsing for several minutes.
  • Still others recommend CankerMelts—an oral patch that you place over the sore that stops pain without numbing the area. It takes about 10 minutes to start working once placed. The disk you place dissolves. Relief lasts 2-6 hours. One study showed that this patch also stopped the sore from growing larger. Another study showed that the sore healed in 3 days vs. 10-14 for untreated ones. CankerMelts are made by Orahealth Corp.
  • There is some evidence that treatment with the Waterlase MD laser (and perhaps other lasers) forms a "bandage" area over the canker sore site and that sites treated with the laser do not have canker sores recur in that same area.

We hope you never get canker sores, but if you do, hopefully these tips will help you! Find out more in the patient education section at 


*This advice is not intended to replace the clinical judgement of your healthcare providers.


Dr. Jennifer Robb is a general dentist who sees both adults and children at her office located at 1320 Cooper Foster Park Rd. Lorain, OH 44053. Call 440-960-1940.

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