Canker Sores in Your Mouth

By Premier Dental of Ohio

Canker sores can be irritating

Canker Sores: How to Avoid Them, and What to Do if You Have One

Canker sores, officially called aphthous ulcers, are a fact of life for many.  These painful ulcers make eating, drinking and speaking terribly uncomfortable.  They come in small, large and cluster variations, and the large ones can last for up to six weeks.  Those of you who get canker sores know how awful they are.  Those of you who do not: thank your lucky stars!

What Causes Canker Sores?

Well, scientists have not yet pinned down an exact cause of canker sores.  This probably means that there is not a single specific cause, but rather a combination of causes.  Most people who experience canker sores regularly get them when their immune system is being challenged by something else.

Nutritional Issues

Some people experience these ulcers when suffering from some type of nutritional deficiency; a zinc deficiency makes you more likely to get ulcers in your mouth.  Other GI problems that cause difficulty for your stomach and intestines to absorb nutrients also put you at a higher risk for canker sores.  Some people with food allergies find that ulcers are a result of eating the food they are allergic to.


An aphthous ulcer is often the result of trauma to the delicate tissues inside the mouth.  If you accidentally bite the inside of your cheek or the side of your tongue during chewing, the traumatized area could develop a canker sore in response.  Some people even get ulcers after dental treatment, which can be hard on the soft tissue of the mouth.

What Distinguishes Canker Sores from Fever Blisters?

Many people confuse the two, but they are distinct medical problems.  Fever blisters (also called cold sores) are the result of a viral infection with Herpes Simplex Virus type 2 (this is NOT the same virus associated with genital herpes).  They always occur in small clusters and begin as tiny fluid-filled bumps.  The bumps eventually burst, leading to a cluster of painful ulcers.

Location, Location, Location

Because aphthous ulcers can occur in clusters, too, the only visible distinction between canker sores and cold sores is in the location.  They do not occur in the same places.  Fever blisters and cold sores (the ones caused by a virus) only occur on the outer edges of the lips and on attached gum tissue.  This means the gum tissue that is adhered to the underlying jawbone and is not movable.  The most common intraoral site for cold sores is on the roof of the mouth.

Canker sores/aphthous ulcers only occur on the movable gum tissue, called the unattached gingiva, the inside of cheeks and the tongue.  Your dentist is able, with one quick look, to tell you whether you’re dealing with a canker sore or a cold sore.

How Can You Prevent Canker Sores?

Since we do not know the exact cause, it is impossible to always prevent canker sores.  However, you can reduce your risk of them by addressing the common predisposing risk factors.

  1. Keep your immune system healthy. Eat a healthy, balanced diet that is a source of all of the necessary vitamins and minerals.
  2. Address any medical problems that would affect your immune system and nutrition. When your body is busy fighting systemic diseases (like diabetes), you are more prone to ulcers and sores in the mouth.
  3. Avoid food allergens. If you know that you are allergic or intolerant to a certain food, stay away from it.
  4. Wear a protective mouthguard during contact sports or activities and a nightguard during sleep. Protect the tissues lining the inside of your mouth from friction and trauma by wearing protective appliances.

How to Reduce the Pain of Canker Sores

If you already have a canker sore and need help with the discomfort, following these instructions will help address the pain.

Things to Avoid:

The following food and drink items will aggravate the pain of a canker sore, so you should avoid them.

  • Acidic foods like tomato and citrus products
  • Spicy foods
  • Hot (high temperature) foods and drinks
  • Carbonated beverages (anything fizzy will burn the ulcer)

Oral Hygiene Considerations:

Many toothpastes and mouthrinses contain harsh chemicals that will hurt when they contact the ulcer.  Make sure you use a mild, non-whitening toothpaste.  If possible, buy one that is SLS-free.  (SLS is sodium lauryl sulfate and a harsh detergent found in most toothpastes to create the foaming action.  Biotene brand is readily available and does not contain SLS.)

When selecting a mouthwash, only use ones that are alcohol-free.  Alcohol not only burns; it also has a drying effect on the oral tissues, which can lead to more cheek-biting and trauma.

Do Try:

When you have a painful mouth sore, there are some steps you can take to alleviate the pain and promote healing.

  1. Hold a small ice cube in your mouth against the ulcer. This produces a minor numbing effect and relieves pain.
  2. Purchase and use Peroxyl mouthrinse (made by Colgate). This formulation is specifically for mouth sores and soothes the tenderness they cause.
  3. Speak to your dentist about a prescription product to place directly on the ulcer. There are several options available, including steroid ointments and soothing mouthrinses.
  4. If the ulcer is the result of a sharp tooth cutting your tongue or cheek, cover the sharp edge with orthodontic wax to prevent more irritation.

More Questions about Canker Sores?

Call your nearest Premier Dental of Ohio location today to schedule a visit with one of our experienced dentists.  Canker sores are painful, and the large ones require medical attention.

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