What are Canker Sores?

Mary McMahon
Mary McMahon

Canker sores are painful areas of ulceration along the delicate inner mucosa of the mouth. The exact causes of these sores are not clearly understood, but they seem to be linked to genetics, oral trauma, and dietary deficiency. Usually, they will go away on their own after a short period of time, but if they are spreading or painful, a medical professional may prescribe topical medication to help reduce the pain and shrink the sores. Canker sores are also sometimes referred to as aphthous ulcers.

Women in their 20s have the highest incidence of canker sores.
Women in their 20s have the highest incidence of canker sores.

A canker sore is not the same thing as a cold sore. Cold sores are associated with the highly contagious herpes virus, and they tend to appear on the lips, around the nose, and on other areas of the face. Canker sores only appear inside the mouth, along the inner lips, lower gumline, inner cheeks, and under the tongue. Typically, they will appear red and irritated, and will sometimes develop a cloudy white covering. They are also not contagious.

Individuals who are suffering with canker sores should avoid chocolate.
Individuals who are suffering with canker sores should avoid chocolate.

Women are more prone to getting canker sores than men, and they usually start to appear in middle childhood. Women in their 20s have the highest incidence, and they usually taper off after that period. For people prone to these sores, avoiding rough foods and sources of oral trauma will help to reduce their incidence, as will consuming more vitamin B12, folic acid, zinc, and iron. They also appear to have a genetic link; if someone in a person's family gets these sores, he or she is more likely to get them as well.

Trauma to the mouth may lead to the development of canker sores.
Trauma to the mouth may lead to the development of canker sores.

When a canker sore appears, it can be quite painful. Many people treat them at home by taking aspirin to reduce the pain, or applying topical analgesic gels directly to the sore. In addition, people with active sores should avoid eating acidic foods and chocolate, which can aggravate the ulcer. Heavily salted and crunchy foods may also be unpleasant to eat. Some foods, like pineapples and mangoes, also contain enzymes that can be irritating.

Cold sores appear around the lips and are not canker sores.
Cold sores appear around the lips and are not canker sores.

If canker sores start spreading, last more than two weeks, or are extremely painful, the person who has them should consult a medical professional. Although they are benign most of the time, these sores can sometimes be an indicator of a more serious medical problem, such as an oral cancer. In addition, a professional can prescribe medications to treat painful mouth ulcers and speed the healing process.

Enzymes found in pineapple can cause the fruit to irritate canker sores.
Enzymes found in pineapple can cause the fruit to irritate canker sores.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I know this sounds crazy, but try putting salt directly on the sore. For me, it's about a minute of intense pain but its basically numb for a while. It's like getting the pain out of the way in one minute that gets dragged out for hours.


@wavy58-- Yea, salty foods are so painful when you have a canker sore. I also can't have anything hot. I basically can't eat on that side of my mouth until it goes away. It's too uncomfortable.

I understand you don't like to numb it, but sometimes it's better than feeling the pain. I don't use any numbing medications but I do put ice on it for a while. It does numb it and ease the pain.

Other than that, I don't really do anything to heal canker sores. I just let it go away on its own.


@andee-- I think that's possible. Canker sores might be showing up when you're stressed because stress weakens the immune system. It's been proven that the hormones which keep the immune system strong are affected when we're under a lot of stress. So I think it could lead to canker sores, especially if you're genetically inclined.

I think eating well, exercising and taking vitamins might help. You might also want to ask your doctor the next time you go for a check up and see what he says.


I used to get canker mouth sores when I was on anti-acid medications for acid reflux. I'm not talking about the calcium carbonate ones for heartburn but proton pump inhibiting drugs like Omeprazole.

I was on this kind of medication for over a year because of severe acid reflux. I didn't know however that when taken regularly, these drugs can prevent the absorption of vitamins and minerals in the digestive tract. So I started getting canker sores in my mouth regularly due to a vitamin deficiency.

When I realize that it's due to the medication, I started taking multi-vitamin supplements. When I got a canker sore, I would take a break from the medication for a few days and the canker sore would go away. Thankfully, my acid reflux is treated now and I'm not on medications. I haven't gotten a canker sore in a long time.


The only kind of canker sore treatment I've ever known a doctor to give out is numbing gel. That just deadens the whole area, which results in the weird feeling that part of your mouth is dead.

I actually prefer the pain to this feeling. Some people think I'm crazy, but I can't stand having no sensation at all, even in one small spot.

As long as I avoid salty chips and tomatoes while I have the sores, I can deal with the discomfort. If I forget and drink something acidic, I am reminded by a sharp pain that lasts several minutes.


I didn't know that canker sores could be caused by trauma until my husband bit his cheek and had one appear. He had never had one before, and he thought that it was just a scar from the bite.

I took one look at it and knew what it was. It had a sunken center with a red ring all around it. The middle was white, and it looked really inflamed.

I congratulated him on getting his first canker sore, and I told him, “Welcome to my world!” He now knows that the pain I complain of when I have them is not exaggerated.


@giddion – A week isn't bad at all. Mine usually lasted about two weeks without any intervention.

I had heard that swishing warm salt water in your mouth could make them go away faster. I tried this, and it was really painful. It's literally putting salt into a wound.

However, my sores did go away much sooner than they had before. I really dreaded swishing with the solution every time that I was about to do it, but the result was worth the pain.


@sunshined – I get temporary canker sore relief by rubbing a paste of baking soda and water directly onto the sores. Oh, it burns when you apply it, but within seconds, it starts to feel better.

The paste will eventually wash away in your saliva, but you can reapply it as often as you like. I put it on my sores two or three times a day.

This seems to make the sores go away more quickly than when I do nothing at all. Still, it takes about a week for them to fully disappear.


This is the first time I have read that canker sores are likely to be genetic. This explains why so many people in my family get canker sores. My husband has never even had one, so he has no idea what they feel like.

As long as canker sores have been around there should be some natural canker sore remedies that would work. I always try to find a natural solution instead of relying on medication, but so far have not found anything that really cuts down on the healing time.

I will have to try the alum spice that was mentioned in a previous post. This would be something that would taste good, and probably wouldn't sting when you put it on.


@andee-- I sure know that stress will give me a cold sore, but have never noticed this with a canker sore. I will get recurrent canker sores for awhile, then will not get any for a long period of time.

I have tried putting topical medication on them, but nothing I used has ever really worked all that well. I just end up waiting for them to go away.

During that time I try to avoid as many salty foods as I can. This can really cause a lot of pain, and you start to really watch what kind of food you put in your mouth.


I wonder if stress will bring on canker sores? It seems like if I am under a great deal of stress, I will get a canker sore.

I am curious if anyone else has noticed this, or if this is just something that happens to me? I have also had what appears to be canker sores on my tongue. These can be really annoying as they affect everything you put in your mouth.


The only way I know how to get rid of canker sores is to let them heal on their own. I have often wondered what causes them and where they come from.

Sometimes I wake up in the morning and realize I have a canker sore. I try to determine if it is something I ate, but I have never been able to narrow it down to any specific food.

I have never had to take any medication for these, but after a few days, they get smaller and eventually just go away. I have never had more than one at a time, and usually just chew my food on the opposite side of my mouth for a few days.


I was told a remedy by a friend a couple of years ago for canker sores and it works like a gem! All you need is the pickling spice alum and a q-tip. Wet the q-tip a touch and then get some alum on it and put it on the cranker sore. It dries it out and it will go away in about 2 days.

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