Canker Sore

Frequently Asked Questions (FAQs)


Why are canker sores white?

Apparently the cause of canker sores isn't entirely clear[1], but may be related to:

A virus

A temporary weakness in your immune system (for example, from cold or flu)

Hormonal changes

Mechanical irritation


Low levels of vitamin B12 or folate

Wikipedia has an uncited and hence somewhat suspect explanation[2]:

The aphthous ulcer appears as a white or yellow oval with an inflamed red border. Sometimes a white circle or halo around the lesion can be observed. The gray-, white-, or yellow-colored area within the red boundary is due to the formation of layers of fibrin, a protein involved in the clotting of blood.

A more reliable source, Robbin and Cotran's Pathologic Basis of Disease, confirms that a canker sore has an "underlying inflammatory infiltrate" (similar to the idea of pus) that "is at first largely mononuclear, but secondary bacterial infection introduces numerous neutrophils." So basically, canker sores look white because there are tons of white blood cells invading them in an inflammatory immune response.


What is the best way to get rid of canker sores?

Try out Rembrant's Canker Sore Toothpaste. It won't get rid of an existing canker sore, but for people who get them all the time, it will severely reduce the frequency at which you get them.


What causes canker sores?

I used to suffer from canker sores regularly, but I am now cured. This is what I found out.

There are a few conditions that can help trigger a canker sore:

Highly acidic foods (esp. orange juice)

Stomach acidity (e.g. bad digestion, heart burn)

Trauma or constant scratching to an area (e.g. biting lips, braces, etc...)

However, none of these is sufficient on its own to create and maintain a painful sore. Each of them has to be combined with the use of a toothpaste containing Sodium Lauryl Sulphate (SLS).

Since I started using SLS-free toothpastes (my favorite is Sensodyne Pronamel), I still get the familiar tingling that is the start of a canker sore if I, for example, bite my lip, but it fades away in less than a day, long before it starts to get painful.


Why do I have recurrent canker sores?

Scurvy is unlikely, although it is possible that you have 'rebound scurvy' which is a temporary case of scurvy that occurs when switching from an extremely high vitamin C intake to a normal intake.

It is more likely that your mouth sores have some other cause than scurvy. Some possible causes include food sensitivities; allergic reaction (you might have a bacterial species in your mouth that you are allergic to or a food allergy); vitamin and mineral deficiency; etc.

They can also occur as a result of other diseases.

Talk to a doctor if they are of concern - diseases that cause malabsorption (such as celiacs disease) can cause deficiencies which can trigger the canker sores.

Though most likely result is that it won't be something that they can treat. You could keep a food/health log, and see if your diet has any deficiency or if there are any food triggers.

Also some people confuse canker sores with cold sores (which are caused by the herpes simplex virus).


What are the best ways to get rid of a canker sore?

As a dentist I see patients with canker sores all the time. Over the counter remedies work on making your mouth for comfortable while the healing process runs it's course. For the occasional sufferer, this is often sufficient.

However some people have recurrent or very large sores that are truly a problem over the longer term. For these people we have several options, two of which are below: 1. Since canker sores are an autoimmune response by the body, we sometimes prescribe a topical steroid such as kenalog in orabase. This calms the body's overactive immune response to allow to lesion to heal more quickly.

2. We can also use topical pain relievers such as Debacterol® which has sulfonated phenolics and sulfuric acid as the main components. Basically it cauterizes the nerve endings in the sore. Though this doesn't speed the healing, at least it helps with the pain during the process.


How have you successfully treated canker sores (aphthous ulcers)?

Celiac disease and candida over growth are two of the most common causes of canker sores, as is metabolic instability. I've dealt with them the most when my hyperglycemia was at an all-time high, along with swollen feet, frequent urination, heartburn.

To treat the symptom, there are plenty of remedies: numbing agents, anti-inflammatories, saline products... but canker sores rarely arrive unaccompanied so if I were you, I'd be paying careful attention to the rest of my ails and go see a nutritionist or a gastroenterologist or a good ol' fashioned, witch-doctor with a whole symptom map.

This really is one of those "smoke to a house fire" grievances. To mitigate, however, try some raw fermentation products: kombucha, sauerkraut, plain yogurt, etc. If it is yeast that's presenting in your mouth, the candida is everywhere and 'eliminating' stuff from your diet (and adding in good probiotics/prebiotics) should alert you to where the trigger/allergen is at. This would be done in the case of Celiac disease, which is really just leaky gut, poor assimilation and dysbiosis of the digestive tract leading to allergic reactions.

But I would see a practitioner who specializes in digestion and pay attention to what else ails. It'll help direct them instead of applying just steroids/anti-histamines that work for a time and taper off.


What is the difference between a cold sore and a canker sore?

A cold sore or fever blister is caused by the herpes simplex virus. You usually find them on the lips in most cases. Between 30 to 90% of the population has this virus in their body by their 30s. It is usually painless.

A cold sore is also infectious, and can spread the virus from one person to another. Triggers for cold sores include stress, UV light, and certain foods. For people who get many cold sores, taking an antiviral drug very early on can help it heal quickly.

Canker sores (aphthous ulces) are thought to be an atypical immune reaction, also caused by stress or certain foods. They can be small (minor) or big (major) and are fairly painful. Usually, the best thing to do is to avoid touching them and wait for them to go away. They will usually go away in less than two weeks by themselves.