Canker Sore Primer Part 1: What is a canker sore?

This is a site about canker sores.  So chances are if you’re on this site, it’s because you did a search, read an article that was passed around, or was led here by one person or another.  Regardless of how you got here, you are probably reading this for two reasons:

Because you have them.  And because you hate them.

So you probably already know what they are.  That’s why I’ve never felt the need to spend time talking about what canker sores are and instead opted to talk about what makes them go away.  But it occurred to me that there are a lot of myths and misconceptions out there about canker sores, and anybody who may be new to them may need a little primer to get clear on what exactly these little demons are before diving into the rest of the website in its wonky, experimental, scientific glory.

So here’s the first in a three-part series of blogs to do just that.  They may be the 3 most informative things you’ve ever read about canker sores.


NOMENCLATURE (a big fancy word for what you call these things)

Canker sores go by many names.  Canker sores.  Mouth ulcers.  Doctory types call it an Aphthous Stomatitis, or an Aphthous Ulcer.  They’re all the same thing.  People who get canker sores on a continual basis have what they call Recurrent Aphthous Stomatitis, or RAS.

I for one prefer to use RAS when I talk about canker sores on this blog because it’s the actual name for an actual condition that canker sore sufferers have.  To me anyway, the goal is not to simply treat canker sores, but to cure RAS to prevent them from happening.

One term you might notice I didn’t include above is “cold sore” or “fever blister” because those are very much different things, which I will talk about below.



There are a million websites out there that talk about the physical characteristics of canker sores, what they look like, what they feel like, usually with a lovely picture of some poor soul pulling down their bottom lip to reveal a nice, disgusting open sore in their mouths.

I don’t know about you, but I don’t really need to see that.

That’s one thing I aim to never publish in this blog – pictures of canker sores.  We all know what they look like and would probably rather never see one again.  So I won’t put you through it.

On the off chance that you’re a reader who doesn’t know what they look like, I will do you the courtesy of linking away to a site that does.  So click here to bring the pain (there’s even a powerpoint you can download).

But here’s how would I describe canker sores to someone who’s never had one:  Canker sores start as a little tickle on a spot in your mouth – an itch, really.  Take a look at the spot and you’ll see that it’s inflamed and red.  Obviously irritated.  Over the next couple of days, the inflammation and redness increase and eventually a small white spot will appear in the center of it.  It’s concave, a crater, sort-of a hole in the tissue of your mouth.  This white spot will grow in size to be anything from a millimeter across to half an inch depending on how lucky you are.

Oh, and it will feel like someone stabbed you in the mouth with a lightsaber.  And never pulled out the lightsaber.

It will be sensitive to touch, painful with spicy foods and any kind of citrus fruits or salts.  Tomatoes will make you pray for sweet death.  This will go on for several days.

In the normal course of things, canker sores will eventually begin to heal after about 7 days.  The ridges around the white center will firm up and begin to creep into the sore, inflammation goes down, and eventually the sore closes up and goes away.  The amount of time it takes to heal mostly depends on how big the sore is.  But average time is between 7-10 days.



Okay, this is by far the biggest misconception out there about canker sores, is people confuse them with cold sores, which are brought about by the herpes simplex virus.  Cold sores are completely different from canker sores in every way, but I’ll break it down to the big three:

1. Cold sores occur on the outside of the mouth.  Canker sores occur inside of the mouth and sometimes (though very rarely) on the lips.

2. Cold sores begin as a blister that then pops and scabs over.  Canker sores never start as a blister and do not scab over.

3. Cold sores are a symptom of a virus and are contagious.  Canker sores are an immune system disorder not associated with any specific virus or bacteria and are not contagious.

If you get the type of ulcers that I described above in this article, you’re not dealing with cold sores.

But still, the confusion persists, and the most common thing any canker sore sufferer gets told is that they have herpes.  And this is just flat-out totally untrue.  Remember this.  Internalize it.  You don’t have herpes.

Can you get canker sores and cold sores?  It’s possible, but one has nothing to do with the other.  You’d just be that unlucky.



Now that we know what RAS is, let’s break down the three types of ulcers:  Minor, Major, and Herpetiform.

It’s pretty basic, really.  Minor Aphthae are smaller than Major Aphthae.  Don’t hurt your brain on that one.

To get more specific, Minor Aphthae (links for the more visually inclined) are anywhere from zero millimeters to half an inch across, mostly falling between 1-5mm.  These are by far the most common, and as described above, heal between 7-10 days and leave no scarring.

Major Aphthae (sometimes known as Sutton’s Disease) have the same physical characteristics as the minor, just much bigger, at around half an inch and larger.  Like any kind of wound, the larger it is, the longer it takes to heal, sometimes around 2-3 weeks, and these do leave scars.  They’re much less common (thank God) than the Minor Aphthae, and some people are more prone to them than others.  People who commonly get the minor ones can have a major one spring up from time to time.

The other type of ulcer is called Herpetiform, and this is a little bit different.  Herpetiform ulcers basically work in clusters.  They are smaller, like small Minor Aphthae, but break out in small clusters of several at a time.  It’s not uncommon for two or more small ulcers very close together to merge into one larger ulcer.  And don’t be fooled by the name, even though they’re called Herpetiform, I don’t believe there’s any relation to them and herpes.  These are by far the most rare form.



Now that we’ve talked about the different types of ulcers RAS sufferers receive, the last thing I’ll talk about here are the different types of RAS sufferers out there.  Canker sore researchers have broken it down into three types – A, B, and C.

TYPE A:  These are the lucky ones.  If you are going to have RAS, this is the best you can get.  Type A people get ulcers infrequently, once or twice a year.  Ulcers are basically an annoyance to be dealt with when they come up.

TYPE B:  These people get canker sores on a consistent basis, rarely going a month without having one.  This is what I am, unfortunately.  Type B people typically get their ulcers in waves, sometimes breaking out with several at once, but then experience periods free of canker sores in between outbreaks.  In my case, I often talk about the “cycles” that I go through of around 10 days each, where the canker sores are “on” for 10 days and then “off” for 10 days.

TYPE C:  These poor unfortunate souls have canker sores pretty much constantly.  Multiple sores at a time, some healing, others beginning, with no periods between sores.


In the next part, we’re going to battle a few more of those misconceptions about canker sores.



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  • Alef

    My treatment for caeknr sores (I assume we are talking about the ones that occur inside the mouth?) is to make sumac tea. Take a bunch of red berries from the stag sumac plant, and put them down into enough cold water to cover, and then rub them a lot to get the little hairs and red coloring into the water. Strain it, and then drink it, swishing it around in your mouth. Within 2 days your caeknr sore will be gone. I live in Indiana and harvest these in September, and hang them in bunches to dry and use all winter. I believe it was a native American remedy.

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