Canker Sores: An Overview
What You Need to Know About Canker Sores (Mouth Ulcers)
(canker sores = Recurrent Aphthous Stomatitis = RAS
= aphthous ulcers = oral ulcers = mouth ulcers)
Canker sores (mouth ulcers) plague the lives of millions. While for some these
small oral ulcerations present only a minor nuisance, for others, canker sores (mouth ulcers) make life
nearly unbearable. The situation is often made worse when a patient's doctor or dentist does not know how to
treat or prevent these ulcers leaving the patient frustrated and in pain.
We see many people who suffer from canker sores (mouth ulcers). In fact, canker sores are very
common affecting nearly 20% of the population.
The good news is that while much remains unknown about canker sores (mouth ulcers), inroads have
been made into effectively preventing and treating these nuisances.
The Difference Canker Sores (Mouth Ulcers) and Fever Blisters (Cold Sores)
Often, canker sores (mouth ulcers) are confused with fever blisters (cold sores). While fever blisters and
canker sores share several features in common (such as the fact that both are very common, often recurrent, and can
be very painful), there are important differences:
Canker Sores (Mouth Ulcers):
Are strictly intraoral meaning that canker sores occur only within the mouth.
- Are not contagious meaning they can not be spread from person to person.
- Are not caused by a virus.
Fever Blisters (Cold Sores), on the other hand:
- Are preceded by small blisters called vesicles.
- Usually occur on the outside of the mouth although they sometimes occur on the inside of the
mouth. When they do occur on the inside of the mouth, fever blisters appear on bound (non-movable)
sections of the mouth such as the mouth roof.
- Are contagious meaning they can be spread from
person to person.
- Are caused by a virus.
It appears that what we eat may influence whether or not we come down with an
episode of canker sores. Some people have allergies to certain foods. Consumption of these foods can lead to canker
sores. Studies show that elimination of these offending foods can sometimes dramatically reduce the number of
canker sore episodes a person experiences.
The Three Classes of Canker Sores (Mouth Ulcers)
The three classes of canker sores refer to the size and duration of the canker
Minor Recurrent Stomatitis:
Small canker sores (mouth ulcers) usually less than one centimeter in diameter. This is the most prevalent form
of canker sores accounting for nearly 70% of all cases. Usually these canker sores heal within 7-10 days with
little or no scarring.
Major Recurrent Stomatitis:
Larger canker sores (mouth ulcers) often greater than 1 cm in size. These canker sores can take longer to heal
(up to three weeks or longer) and may leave scarring after they heal.
Canker sores (mouth ulcers) are pinpoint 2-3 millimeter. Often these pinpoint canker sores merge into larger
ulcerations. This is one of the rarer forms of canker sores.
The first canker sores usually occur between the ages of 10 and 20. During life, episodes usually, but not
always, become less frequent and less severe. Interestingly, women often report increased susceptibility to canker
sore formation during certain times of their menstrual cycle. Some women report complete relief from canker sores
Interestingly, canker sores (mouth ulcers) affect people to varying degrees of severity. Some people may get an
occasional outbreak of canker sores once or twice a year while others may suffer near continuous overlapping
episodes of canker sores (mouth ulcers).
Systemic Conditions Associated with Canker Sores (Mouth Ulcers)
Although the vast majority of canker sore cases are associated with no underlying
illness, in a small percentage of cases, canker sores are indicative of a bodily (systemic) disorder. People
with Behcet's Disease, for instance, will often have canker sores (mouth ulcers) in addition to genital
lesions, eye lesions, and general skin afflictions.
Many people with digestive conditions such as celiac disease, Crohn's Disease,
Ulcerative Colitis, and gluten hypersensitivity will also display canker sores as a manifestation of their
underlying disorder. HIV infected patients may also develop canker sore like ulcers.
In the small percentage of cases where an underlying condition may be suspected, a
careful medical history and examination by a physician will be able to indicate whether canker sores in a
particular patient are associated with an underlying disorder.
What Causes Canker Sores (Mouth Ulcers)?
Current theories on the causes of canker sores have focused on the immune system.
This research suggests that canker sores may be caused by the body's own immune system attacking the cells
lining the inside of the mouth.
Research is being conducted to determine what makes a person susceptible to canker
sores in the first place as well as what actions and mechanisms trigger canker sore outbreaks. Among those
things that may trigger an attack or make a person more susceptible are ingredients in toothpastes, certain
allergies to food products and preservatives, trauma from overzealous brushing or lip biting, and
Treatment of Canker Sores (Mouth Ulcers)
Usually canker sores clear within 7-14 days without treatment. During this time, however, the canker sores can
be painful especially when people eat or drink. Treatment helps ease the pain and may help reduce the amount of
time it takes for the ulcers to go away.
Conventional treatments usually fall into three categories:
- Corticosteroid Rinses and Gels: Often prescribed by
a dentist or physician for severe or painful cases, these medications have proven extremely effective. A
topical prescription steroid (non-alcoholic) gel of lidex applied lightly to the ulcer 2-4 times daily is
commonly prescribed. The biggest downside to the medication is that it hurts upon
- Analgesic (Pain Relieving) and Protective Ointments and
Gels: These are pain relieving medications which can be purchased at your local drug store. These include
compounds such as Zilactin or Oragel. Many of these compounds, after being applied, dry forming a protective
cover over the sensitive ulcerations.
- Anti-microbial Mouthwashes: Surprisingly the use of
anti-microbial mouthwashes has provided effective relief for many. Canker Sores are not caused by a bacteria or
virus so the mechanisms by which these anti-microbial mouthwashes work remains unclear. Commonly prescribed are
anti-microbial mouthwashes containing the active ingredient chlorhexidine gluconate.
On the Subject of Preventing Canker Sores (Mouth Ulcers)
Trauma to the inside of the mouth
can trigger an outbreak of canker sores. This trauma includes overzealous tooth brushing, biting your
cheek or tongue, and scraping the inside of your mouth with hard or sharp foods (like hard pretzels). Because
Stress is another factor capable of triggering canker sores. We advise those patients
susceptible to canker sores to try to reduce the stress in their lives. In today's society this is often easier
said than done. Its well worth the effort, however, since reducing stress has other health benefits as well.
Research suggests that reactions to certain food products may be responsible for many cases of canker sores.
Among the foods that may cause canker sores in certain people are: nuts, peanut butter, sea food, wheat
products, chocolate, and milk.
Also implicated as a factor for canker sore occurrence are deficiencies in certain vitamins and minerals -
principally B12, iron, and folic acid. Several British studies have shown deficiencies in these levels of
vitamins / minerals in a significant number of canker sore sufferers. U.S. studies, however, do not show the same
correlation between levels of these vitamins / minerals and canker sore occurrences.
One of the most exciting advances has been the establishment of the link between canker sores and an ingredient
common to almost all toothpastes. The additive SLS or sodium lauryl sulfate may be a culprit in
canker sore formation.
SLS (sodium lauryl sulfate) acts just like a detergent. It is used in the laboratory as a membrane destabilizer
and solubilizer of proteins and lipids. SLS is used in toothpaste to emulsify (mix) oil and water based ingredients
together. In your toothpaste it creates the foam you get when brushing.
The thought is that SLS may, in susceptible individuals, cause microscopic trauma or membrane disruption to the
skin cells in the mouth. This along with trauma or actions of the immune system may lead to canker sore
Although these are only preliminary studies and more research needs to be done, it does offer hope.
Many of my patients and my wife have benefited greatly from using toothpastes which don't contain SLS. We
recommend Enamel Saver toothpaste which
does not contain SLS.
Incredibly, many of the visitors to this website have e-mailed thanking us for the tip about SLS free toothpaste
which had immediately made an impact by dramatically reducing the number of canker sores they experienced!
To learn more about the relationship between SLS and canker sores see our SLS article.
Keeping a Canker Sore (Mouth Ulcer) Diary
What can you do if you suspect one of the above factors may be causing your canker
sores? We suggest keeping a Canker
Sore Diary. This is a simple notebook in which you keep track of the toothpaste you use, the foods you
eat, stressful events, and any trauma that may occur to the inside of your mouth. In the same notebook keep a
record of the number of canker sore occurrences.
By keeping this notebook you may be able to correlate a specific factor to the cause
of your canker sores.