Canker sore or cancer

Canker Sores

Canker sores (recurrent aphthous stomatitis, RAS) are among the most common of oral conditions and are experienced by more than half of the population. These small, round or oval, painful yellowish sores often first appear in adolescence.

They usually affect the softer parts of the mouth that move, such as the tongue, soft palate, cheeks, and lips. This condition is recurrent because these sores usually will heal on their own but then reappear in the same or new locations after a period of time. In some severe cases, old ulcers may be healing while new ones appear.

There are three main forms:

Minor Aphthous Stomatitis: this is the form that affects more than 80% of canker sore sufferers. The sores are usually small (less than 1 centimeter in diameter), heal in about a week, and do not cause scarring.

Major Aphthous Stomatitis: this more severe form affects approximately 15% of patients with canker sores. These sores often last two weeks or more and are typically over 1 centimeter in diameter. They can be extremely painful and often heal with scarring.

Herpetiform Aphthous Stomatitis: This form of the condition is uncommon, occurring in less than 5% of people with canker sores. They occur as clusters of very small ulcers (less than a millimeter in some cases) that sometimes merge together to form larger ulcers. They usually heal in just over one week.

Most of the time, canker sores are self-limiting. This means that they will go away even without treatment. The cause of canker sores is not known. However, in some instances, they can be a sign of other conditions affecting the body (such as a gastrointestinal disease). Be sure to tell your doctor if you are experiencing fatigue, abdominal pain, fever, eye discomfort, or have rashes or sores on other parts of your body.

A Typical Minor Aphthous Ulceration More Extensive Major Ulcerations


Q: Is the condition contagious? Did I catch it and can I give it to anyone else?
A: No. This condition is not like herpes and cannot be transmitted, even if you have open sores.

Q: How can I tell the difference?
A: The location is a good clue. Your doctor may recommend performing culture testing or a biopsy to be certain.

Q: Then what causes canker sores?
A: No one really knows, but it is thought to be caused by an immune system malfunction that causes white blood cells to temporarily attack the mucosal cells lining the mouth. Sometimes they are a form of allergic reaction to food ingredients or components of toothpastes or mouthwash. Canker sores can also be associated with some systemic conditions such a Crohn’s disease and nutritional deficiencies.

Q: How can I tell if my canker sores are related to an allergy or systemic condition?
A: Your doctor can often make this diagnosis after carefully assessing your medical history. Sometimes simple blood tests may be required to see if you have a nutritional deficiency, or your doctor may suggest allergy testing.

Q: Is there a cure for canker sores?
A: Not yet. However, therapies are available to decrease pain, shorten the time of the ulcers, and even reduce how often they occur. These range from creams applied to the sores to stronger systemic medications.

Q: Can anything prevent them?
A: The best way to attempt preventing them is to keep an ulcer diary. By writing down when you have outbreaks of canker sores, you may find that there are connections between your diet, toothpaste, or lifestyle. You should share this information with your doctor as it may help him or her develop a more effective treatment strategy.

Q: What about “canker sore toothpastes”?
A: These lack a detergent known as SLS (sodium lauryl sulfate). In some patients, using an SLS free toothpaste reduces the frequency of outbreaks.

Q: When should I talk to my dentist about my Canker Sores?
A: If you experience more than three canker sore outbreaks per month, if you are never without an ulcer, or if you have any symptoms listed in this sheet or feel that there could be other factors connected to your canker sores

Q: I see many canker sore medicines in the store. Is one better than the other?
A: While there are numerous products marketed to treat canker sores, there is no perfect product and there are few well designed trials comparing the efficacy of these products against each other. A product that works well for you may not work well for someone else. You should advise your dentist of any products you have used or are currently using to treat your canker sores. A summary of commonly recommended therapeutic agents is discussed in the Patient Information Sheet “Treatment of Canker Sores”

Prepared by the AAOM Web Writing Group
Updated 31 December 2007

Japanese Translation – 日本語訳
Spanish Translation – Traducción Español

The information contained in this monograph is for educational purposes only. This information is not a substitute for professional medical advice, diagnosis, or treatment. If you have or suspect you may have a health concern, consult your professional health care provider. Reliance on any information provided in this monograph is solely at your own risk.

Dealing with a Sore Subject: Cold Sores and Canker Sores

When a child’s mouth hurts, it makes it tough to eat or drink. General crankiness usually comes along, too. Cold sores and canker sores are common causes of lip and mouth pain. However, you have to know the difference to know how to best care for these painful annoyances.

Cold Sores 101
Your child says her lip feels funny — like a tingling or burning. The next day, she wakes up with a reddish blister on her lip. She likely has a cold sore, also known as a fever blister.

Cold sores are caused by the Herpes simplex type 1 virus (HSV-1). This very common virus is transmitted through saliva. Kids can catch the virus easily, whether by kissing a person with a cold sore or by sharing a glass, utensils or a towel. Some people infected with the virus never have any symptoms. Others have periodic flare ups. Although dormant, the virus stays in the body and can be reactivated any time, usually during a time of illness, stress or even too much sun.

A cold sore, while harmless, can be uncomfortable. The cold sore may appear as a blister or even a cluster of blisters on the lips or around the outside of the mouth. The area may be swollen and tender and make eating and drinking painful. Within about 7 to 10 days, the blisters will dry and form scabs as they heal.

To alleviate pain, you can give your child over-the-counter pain relievers like Tylenol or Motrin. (Do not give aspirin.) Cold or ice packs on the sore can make your child feel better, too. However, don’t use cold sore ointments without your doctor’s advice.

It’s also important to discourage your child from picking at a cold sore. The virus is easily spread to other parts of their body like the eyes. Remind your child to wash his or her hands often, too.

Canker Sores 101
Canker sores are different than cold sores, but they can also make eating and even talking uncomfortable. These small, shallow round sores are white or gray with a bright red circle around them. They’re usually found on the tongue, the lining of the mouth or on the gums.

Most canker sores are relatively minor with simple causes like eating acidic or spicy foods such as citrus fruits, pineapple, grapes and tomatoes. Other causes are from biting the inside of the cheek or lip, or other abrasions such as braces rubbing the cheeks, stress, hormonal factors, reactions to some medications, or from viruses or bacteria.

The good news is canker sores usually only last about a week. To reduce pain and swelling, you can give your child an over-the-counter pain medication such as Tylenol or Motrin or try sucking on ice pops. To help prevent canker sores, avoid the irritating foods or rinse your child’s mouth with warm water after eating.

Checking In
As with any illness, if your child’s sores — whether cold sores or canker sores – have not improved after a week or symptoms have worsened, call your pediatrician.

What Are Canker And Mouth Sores?

What are Mouth Irritations and Oral Lesions?

Mouth irritations and oral lesions are swellings, spots or sores on your mouth, lips or tongue. Although there are numerous types of mouth sores and disorders, among the most common are canker sores, cold sores, leukoplakia and candidiasis (thrush). These are discussed below. If you have a mouth sore, you’re not alone-around one third of all people are affected at some point. Nonetheless, mouth sores, irritations and lesions can be painful, unsightly and can interfere with eating and speaking. Any mouth sore that persists for a week or more should be examined by your dentist. A biopsy (tissue taken for testing) may be advised and can usually determine the cause, ruling out such serious diseases as cancer and HIV.

How do I Know if I Have a Mouth Sore or Oral Lesion?

The following signs may indicate a mouth sore or oral lesion:

  • Canker sores are small white swellings or sores surrounded by an area of redness. While canker sores are not contagious, they are often confused with cold sores, which are caused by the contagious herpes virus. It may help to remember that canker sores occur inside the mouth, while cold sores usually occur outside the mouth. Canker sores can recur, and can be minor (small), major (larger) or herpetiform (multiple, in groups or clusters). Canker sores are common and often recur. Although the exact cause is uncertain, some experts believe that immune system problems, bacteria or viruses may be involved. Factors such as stress, trauma, allergies, cigarette smoking, iron or other vitamin deficiencies, and heredity may also make one susceptible.
  • Cold sores, also called fever blisters or herpes simplex, are groups of painful, fluid-filled blisters around the lips and sometimes under the nose or around the chin. Cold sores are usually caused by a type of herpes virus and are very contagious. The first infection often occurs in children, sometimes without symptoms, and may be confused with a cold or flu. Once a person is infected, the virus stays in the body, occasionally causing recurrent attacks. For some people, however, the virus remains inactive.
  • Leukoplakia looks like a thick, whitish-color patch on the inner cheek, gums or tongue. It is often associated with smoking and smokeless tobacco use, although other causes include badly fitting dentures, broken teeth and chewing on one’s cheek. Because an estimated 5 percent of leukoplakia cases progress to cancer,* your dentist may take a biopsy. Leukoplakia often heals when tobacco use is stopped.
  • Candidiasis — oral thrush — is a fungal infection caused by candida albicans (a yeast). It can be recognized by the creamy, yellow-white or red patches that occur on moist surfaces in the mouth. Tissues under the patch can be painful. Thrush is most common among denture wearers, newborns, those debilitated by disease and those whose immune system is not functioning properly. People who have a dry mouth, or who are taking or have just completed antibiotic treatment, are also susceptible.

How are Mouth Irritations and Oral Lesions Treated?

Treatment varies according to the type of condition you have. For the most common types of mouth sores and disorders, described above, treatment is as follows:

  • Canker Sores — canker sores usually heal after seven to 10 days, although recurrent outbreaks are common. Non-prescription topical ointments and pain relievers can provide temporary relief. Rinsing with antimicrobial mouth rinses may help reduce the irritation. Sometimes, antibiotics are prescribed to reduce secondary infection.
  • Cold Sores — the blisters usually heal in about a week. Because there is no cure for herpes infections, the blisters may reoccur during times of emotional upset, exposure to sunlight, allergies or fever. Non-prescription topical anesthetics can provide temporary relief. Prescription antiviral drugs may reduce these kinds of viral infections — ask your dentist or physician.
  • Leukoplakia — treatment begins by removing the factors causing the lesions. For some patients that means quitting tobacco use. For others, it means removing ill-fitting dentures and replacing them with properly fitting ones. Your dentist will monitor your condition, examining the lesion at three to six month intervals, depending on its type, location and size.
  • Candidiasis — treatment consists of controlling the conditions that cause the outbreaks.
    • Cleaning dentures is important in preventing denture-induced problems. Removing dentures at night can help
    • If antibiotics or oral contraceptives are the cause, reducing the dose or changing the treatment may help
    • Saliva substitutes are available to help with dry mouth
    • Antifungal medications may be used when the underlying cause is unavoidable or incurable
    • Good oral hygiene is essential
Fever Blister Canker Sore

* The Complete Guide to Better Dental Care, Jeffrey F. Taintor, D.D.S., M.S., and Mary Jane Taintor, 1997.

Is It a Canker Sore or Something Else?

A small lesion in the mouth is most likely a harmless canker sore. But if it doesn’t improve within a couple of weeks, it’s time to see a doctor or dentist to make sure it isn’t something more serious.

A canker sore is not the same thing as a cold sore. Alamy

Canker sores are lesions that can develop on the soft palate inside the mouth and on the gumline. Most canker sores are small, measuring less than 1 millimeter in diameter, and they usually appear white or yellowish in color with a red border. (1)

These lesions are common. (2) But don’t assume that every sore in or around your mouth is a canker sore, especially since a number of conditions can look like a canker sore but actually represent something more serious, says Chirag Shah, MD, co-founder of Accesa Labs, a website that helps improve access to affordable medical lab testing.

Not sure what that white spot in your mouth is? Here’s a look at conditions that could be confused with a canker sore.

Cold Sores

What you believe to be a canker sore could actually be a cold sore. Also known as fever blisters, cold sores are painful blisters with similar characteristics to canker sores. (3) But canker sores differ from cold sores, which are caused by the herpes simplex virus (HSV-1), in that they are not contagious and don’t form on the keratinized tissues of the oral area (such as your lips), explains Samantha Rawdin, DMD, a prosthodontist based in New York City.

Some people get a cold sore after coming into contact with the virus through a kiss or after sharing a drink or food with someone who’s been infected. (2)

Cold sores can be unsightly, but the good news is that they usually heal in about two to four weeks, although sores may recur. (3)


These lesions can also be mistaken for canker sores because they produce white spots or patches inside the mouth.

Unlike a canker sore, leukoplakia patches aren’t sensitive or painful. (4) This condition can be harmless like a canker sore, but some patches may become cancerous. In fact, roughly 3 to 17.5 percent of people who have leukoplakia eventually develop squamous cell carcinoma. (4) So if you have this condition, your doctor may recommend a biopsy to rule out cancer.


Most canker sores go away in less than 14 days. (2) If a canker sore persists after that period of time, it increases in size, or you’re concerned about a particular sore, a medical evaluation is warranted, says Dr. Shah.

A sore that doesn’t heal could be erythroplakia, a lesion that causes a white or red spot inside the mouth. These spots, however, are more serious because some can be precancerous or cancerous. (5) The cause of erythroplakia is unknown, but the condition has been linked to smoking and tobacco use.

Lichen Planus

If you develop a tender white spot that also itches, you may have lichen planus instead of a canker sore. The spots are sometimes accompanied by a lacelike white patch on the inside lining of the cheeks. What’s interesting about this condition is that it affects more than just the inside of the mouth. If you have lichen planus, you’re likely to notice itchy bumps or spots on different parts of your skin. (6)

This is an inflammatory condition that’s believed to result from an abnormal immune response, when the immune system attacks cells of the skin and the mucous membranes. (6)

Oral Thrush

Oral thrush, also called oral candidiasis, is a fungal infection that causes white patches on the inside of the mouth. This condition can be painful and is sometimes accompanied by a loss of taste, a burning sensation, bleeding gums, and difficulty swallowing. (7)

Oral thrush occurs when yeast reproduces rapidly inside the mouth, usually the result of a weak immune system. This might happen if you’ve been prescribed antibiotics or are taking a medication that suppresses your immune system. (7)

Oral Cancer

If you have a sore that doesn’t improve after a couple of weeks or worsens, see your doctor or dentist. What appears to be a canker sore could actually be oral cancer.

Oral cancer can also cause small white ulcerations inside the mouth. These lesions can be painful and gradually become thicker. (8) Early diagnosis is important to prevent oral cancer from spreading to other parts of the body such as the lymph nodes.

Keep in mind that while canker sores usually develop on the soft palate inside the mouth, oral cancer can also form on the hard palate and tongue. (8)

A sore might be oral cancer if you have other symptoms as well — such as a fever, throat numbness, or hoarseness — or if you have a history of smoking and other tobacco use. A biopsy of the lesion can diagnose or rule out cancer. If testing confirms cancer, your doctor will use imaging tests (such as an MRI or CT scan) to see whether the cancer has spread to other parts of your body. (9)


This is a painful infection of the mouth and gums that can develop after the first exposure to HSV-1, the same herpes virus that causes cold sores. Gingivostomatitis can occur in anyone, but it is more common in children 5 years old and younger. (10) About 90 percent of people have been exposed to the HSV-1 virus before age 50. (11) But not everyone will develop gingivostomatitis, and not everyone develops cold sores as a result.

Similar to a canker sore, gingivostomatitis can cause a small red or white sore on the soft palate, on the gums, or inside the cheek. But unlike a canker sore, this condition can also cause a fever and bleeding gums. Bad breath is also a common sign.

These sores are temporary and often go away in about two to three weeks without treatment. But taking an oral antiviral such as Zovirax (acyclovir) may shorten the duration of the sores if taken within 72 to 96 hours of onset. (10)

Don’t Ignore Suspicious Mouth Sores, Especially Those That Last

A single sore inside your mouth is probably a canker sore, which is harmless and short-lived. Even so, keep a close eye on the lesion. If it doesn’t go away or grows in size, it might be something more serious. And the sooner you see your doctor or dentist for a diagnosis the better. An early diagnosis leads to early treatment, and possibly a better prognosis if the lesion is precancerous or malignant.

How to Identify the Signs of Mouth Cancer

Are you familiar with the signs of mouth cancer? According to the National Institutes of Health, 2.9 percent of all cancers involve the pharynx and the oral cavity, which includes the mouth, tongue and throat. But some things can put you at higher risk than others. Smoking and drinking, for example, both increase your risk. Older individuals are also more susceptible, often due to past health habits and a naturally lower resistance to infection.

The Sore That Won’t Go Away!

The mouth takes a lot of wear and tear. Hot and spicy foods can create burns, whereas hard food products and poor brushing technique can cause abrasions to the cheeks and gum tissue. Luckily, this kind of trauma will usually heal in seven to 14 days. Some sores are even painless and just appear red or white, or a combination of both. These also may improve over a two-week time period. If the sore in the mouth persists, however, it needs to be checked by a dentist.

Bump in My Mouth

Any swelling or bump on the tongue that isn’t from certain trauma should be evaluated by your dentist too. A bump can appear on the sides, bottom or top of the tongue. Sharp teeth or dental restorations may be the cause, but only a dentist can rule this out. Bumps may also show up on the inside of the cheeks and on the lips. Several reasons cause bumps to form in these areas and not all of them are signs of mouth cancer. You can sooth these bumps with gentle, alcohol-free formulas like Colgate Peroxyl Mouth Sore Rinse, which is also effective for soothing canker sores and even irritation brought on by ongoing oral cancer treatment. The product’s bubbling action cleans and alleviates discomfort to promote healing.

Self Evaluation

Unlike other parts of your body, it’s not easy to do a real self examination. You need a mirror and good lighting to see the surfaces of your mouth. Even then, there are many places that just won’t be visible. You can also use your index finger to feel for bumps, but without visual inspection, this method will not yield much as to the source of the problem.

Oral Cancer Screening

Your dentist is trained to perform screenings for oral cancer. He or she may use visual inspection, special scopes, lighting equipment or staining to locate abnormal tissue. Dental x-rays can also help identify risk for mouth cancer. If you feel you’re showing symptoms, you should request a screening at your dental visits. This is especially important if you smoke, chew tobacco, consume alcohol on a regular basis or have a combination of these three habits.

The Biopsy

If abnormal tissue is found in your mouth, a biopsy may be conducted to surgically remove all or part of the abnormal tissue. It is then sent to a pathologist for evaluation under a microscope. These evaluations look for cancerous cells that have been able to enter your oral tissue, and additional tests can be performed to decide on the right course of treatment.

The Good News

The number of cases of mouth cancer due to tobacco use is in decline, according to The Oral Cancer Foundation. So if you smoke, join the trend and seek help to quit. Better still, the survival rate following the early detection of mouth cancer is high. If you have a mouth sore or abnormal-looking spot in your mouth that lasts more than two weeks, see your dentist for an oral examination.

Finding a strange change in your mouth can be scary. You might not know why a mark has appeared, how long it will be there, or what it is. Since it could be a variety of different things, ranging from harmless to more serious, it’s important to visit a dentist or doctor when you find an unfamiliar sore or spot in your mouth.
In the meantime, you might want to get a better idea of two common but very different types of oral issues that often get confused: mouth cancer and canker sores. Today, our dentists are going to break down the difference between mouth cancer and canker sores so that you can better identify what’s going on in your mouth.

What Mouth Cancer Looks Like

Surprising to many, mouth cancer can grow in your mouth just like it can anywhere else in your body. According to the American Dental Association (ADA), those who use tobacco and/or drink are more likely to develop mouth cancer, as are people over the age of 44 and, more specifically, men. HPV is also the leading cause of cancer at the very back of the mouth and throat (technically known as oropharyngeal cancer).
Mouth cancer typically affects your cheeks, lips, tongue, or throat. It usually shows up as flat, white patches on any of those areas. These patches are made up of cells that can lead to cancer. Mixed red and white patches and bright red patches are also signs of trouble.
Mouth cancer patches can be rough and hard to scrape off. These areas can also be benign, but it’s always important to have a dentist check to make sure. also notes that painless ulcers, or canker sores, that don’t heal can be a form of mouth cancer. The ADA suggests getting your mouth checked out if signs and symptoms of mouth cancer persist after two weeks.
Finally, cancer in the throat may cause symptoms such as difficult or painful swallowing, a swollen but painless tonsil, an ongoing sore throat or hoarse voice, a painless lump on the outside of your neck that has been there for at least two weeks, and constant coughing, according to the Oral Cancer Foundation.

What Canker Sores Look Like

Unlike mouth cancer, minor canker sores are virtually harmless, except for the annoying discomfort they can cause your mouth. They may be caused by several things, including stress, hormonal shifts, food sensitivities, and toothpaste, according to the Mayo Clinic.
The defining difference between canker sores and mouth cancer is pain. Canker sores can be extremely painful. Thankfully, the pain tends to lessen over a few days, and the sore usually heals up by itself within two weeks.
Canker sores also look different than patchy mouth cancer. A canker sore looks like an ulcer or sore. They are typically round with a depressed center and may appear to be white, grey or yellow. The outer rim of the canker sore is typically red.
If you have a canker sore that doesn’t heal within three weeks, you should see a dentist, according to Mouth cancer can appear in the form of an ulcer.
Do you have a sore you would like us to take a look at in Chicago? Contact Water Tower Dental Care! We’re experts on identifying mouth cancer vs. canker sores.

Sick with the flu, graphic designer Lisa Bourdon-Krause paid a visit to a walk-in clinic in 2000. While there, she showed the doctor her tongue: A nickel-sized white-and-red spot on the rear left side had been bugging her for weeks whenever she chewed or swallowed. The physician suspected a virus and prescribed antibiotics.

Bourdon-Krause finished the meds, but the lesion persisted stubbornly. At her dental checkup a month later, her dentist took one look and sent her for a biopsy. The diagnosis: oral cancer. Surgeons would need to remove about half her tongue to ensure they got all the cancer, and although they’d try to reconstruct it using forearm tissue, she might never speak again.

“I was devastated that my 2-year-old son might grow up never hearing my voice,” Bourdon-Krause recalls. Unable to sleep the night before entering the hospital, she stayed up recording messages to her son: “Happy birthday. I love you forever.”

When she awoke from surgery, her tongue was swollen and metal sutures lined the middle. A few days later, she tried to speak. “I was coherent,” she says, “and thrilled!”

Oral cancers are un?common but on the rise, and research has found a new culprit: human papillomavirus (HPV) strains 16 and 18, which may account for up to 30 percent of all cases. Both genders can pass the virus through oral sex. Bourdon-Krause doesn’t know if she had HPV, but she wants doctors to know how to spot related cancers. “I showed the doctor at the walk-in clinic a photo of my tumor and said, ‘This is oral cancer.'”

Lower your risk for oral cancer

Prevent it Consider Gardasil, a vaccine that protects against HPV 16 and 18, strains linked to oral cancers.

Screen it Ask for an oral cancer screening at your regular dental checkups; general practitioners may miss it.

Spot it See your doc if any of these signs persist for more than two weeks…

  • A red or red-and-white sore or a painless patch of discolored tissue anywhere inside your mouth.
  • Difficulty chewing or swallowing.
  • Any alteration in your voice.
  • A persistent earache on one side.
  • A painless hard lump under your jaw that doesn’t go away.

What to Do When You Have Recurrent Canker Sores

What causes mouth ulcers?

Also known as canker sores these are little crater-like spots inside the mouth and lips or on the tongue. If they keep on coming back, it might be due one or more of the following factors:

  • Certain food groups: wheat, chocolate, citric acid, spicy foods or those eaten very hot
  • Irritation from foreign objects in the mouth like poorly fitting dentures or braces
  • Hormonal changes e.g. during menstruation or pregnancy
  • Biting one’s own tongue or cheek accidentally
  • Using toothpaste containing a chemical called sodium lauryl sulphate
  • Stress

Recurrent mouth ulcers

Recurrent canker sores come back at frequent intervals, not necessarily in the same spot. Carefully monitor your oral health routine and the foods that you consume, perhaps there you will find a clue as to why canker sores have become recurrent. If they keep returning, it’s probably best to consult your doctor or dentist as they could be caused by underlying health conditions such as:

  • Viral infections like cold sore virus or chickenpox
  • Iron deficiency
  • Vitamin B12 deficiency
  • Crohn’s disease
  • Coeliac disease
  • Weakened immune system result of HIV or lupus
  • Reactive arthritis

Another reason can be some medicines like beta-blockers, non-steroidal anti-inflammatory drugs, or treatments like chemotherapy or radiotherapy.

If canker sores last more than three weeks, are particularly red/painful/large or keep coming back then it’s worth seeking medical advice.

Most of the time canker sores are harmless and don’t require any particular treatment. Avoid anything that might irritate that area (rough food or toothbrush bristles) and simply wait for it to get better. However if they last more than three weeks, are particularly red/painful/large or keep coming back (i.e. recurrent canker sore bouts) then it’s worth seeking medical advice.

Here are a few things you can do at home that may relieve any pain and irritation from mouth ulcers or canker sores:

  1. Apply a protective gel recommended by your pharmacist
  2. Drinking or eating cold or frozen foods, or applying ice directly can numb the area reducing pain and maybe even inflammation.
  3. Avoid foods that might irritate the affected part of your mouth: rough foods like crusty bread or crisps can be problematic, likewise spicy, hot or acidic mouthfuls
  4. Use a toothbrush with soft bristles to avoid harming the mouth tissue
  5. Use a mild toothpaste that promotes good bacteria in the mouth and does not contain sodium lauryl sulphate
  6. It’s difficult to get rid of canker sores quickly, but you can help keep them away by ensuring good oral hygiene habits including cleaning your teeth at least twice a day, flossing and using antimicrobial mouthwash. Read more on our article about how to reduce canker sores.

Those are a few top tips, but they are no substitute for seeing a healthcare professional. If you are in any doubt simply visit your doctor or dentist for further advice.

How to identify canker sores.

– Lesion characteristics and locations. / Stages of formation. / Pictures. / Outbreak frequency and incidence rates. / Normal healing characteristics.

Canker sore
identification. Canker sore

Canker sore / Aphthous ulcer identification.

Dentists distinguish canker sores (specifically “recurrent minor aphthous ulcers,” the type of canker lesion that affects 80% of sufferers) from other types of mouth sores by way of:

  1. Their appearance.
  2. Their location and the type of tissue on which they’ve formed.
  3. The fact that they are recurrent (have been experienced repeatedly).

Patient history also plays an important role in identification and differentiation from other lesions. – A person’s dentist will be interested in signs and symptoms that did, and specifically did not, take place. Both immediately preceding, and then throughout the stages of their ulcer’s formation and ultimate healing process.

No medical testing (e.g. biopsy, culturing) is typically involved in making a diagnosis. All of the above findings, collectively, can be expected to provide ample evidence for identification on their own. The microscopic characteristics of canker sores are non-specific.

What do canker sores look like? – The stages.

Note: The time frames we’ve assigned to the different stages outlined below overlap, due to the fact that what is experienced by any one person varies.

Stage 1 – (2 to 48 hours duration)

The earliest indication of pending canker sore formation doesn’t involve visible signs.

Instead what is noticed is a sensation of tingling, itching, burning or numbness in the area where the lesion will ultimately form. (These signs are referred to as “prodromal” symptoms.)

Stage 2 – (18 to 72 hours duration)

During this time frame, the first visible signs of the developing lesion will have started to show.

  • The area where the sore will form begins to transform into a reddened circular area on the skin. (Formally referred to as an “erythematous macule.”)
  • As the lesion’s development progresses, the macule may transform into a small, possibly whitish, papule (solid, slightly raised area).
  • During this stage, the area will begin to ulcerate and enlarge. (The process of ulceration begins in the skin’s basal layer and then advances into the more superficial layers above.)

Pictures of canker sores (aphthous ulcers).

Stage 3 – (1 to 14 days duration)

By this stage in its development, the lesion has transformed into a fully-formed ulceration (involves multiple layers of skin tissue). It may continue to grow in size for 4 to 6 days.

Appearance (of the typical fully-formed canker sore).

  • In basic form, the lesion is a single shallow ulcer having a symmetrical round or oval shape. (Multiple simultaneous lesions are possible.)
  • Canker sores are typically no more than 1/4 inch in diameter (3 to 5 mm).

The physical characteristics of a canker sore.

Sores have a grayish membrane-coated central ulceration with a surrounding red border. The skin around the lesion looks normal.

  • The lesion’s center (the ulceration) develops a loosely attached membrane-like covering (a pseudomembrane) that can be easily dislodged.

    (The membrane is pyogenic in nature, meaning it’s composed of cells, compounds and debris originating from the inflammatory process that has caused the ulceration.)

  • Initially, the membrane has a primarily yellow-white coloration. As healing ultimately progresses, it will tend to take on more of a grey-white tint.
  • A border comprising a band of erythematous (reddish) tissue will surround the ulceration.

    The outline of this red halo is characteristically circumscribed (well defined) and regular (not jagged).

  • The skin that lies outside the lesion’s reddened border will appear normal and healthy.

Other characteristic signs and symptoms.

  • Canker sores usually are painful. The level of discomfort that’s experienced may seem out of proportion with the lesion’s size.

    Sufferers will frequently limit their oral movements, the types of foods they eat and favor the sore’s surface so not to trigger pain.

  • There are no distinguishing systemic features associated with minor aphthous ulcers, such as the person having malaise (generally feeling poorly) or fever.

▲ Section references – Neville, Akintoye, Chavan, Casiglia, Scully, Dunlap

Can a person have more than one lesion at a time?

Yes, outbreaks of multiple, simultaneous canker sores may occur.

  • Usually, the maximum number of sores that will form at one time will be six or fewer.
  • If multiple canker sores do develop, they’re more likely to be distributed as opposed to being clustered together.
  • In the case where two sores do form adjacent to each other, they may combine into a single larger and irregularly shaped ulcer (as opposed to the classic round or oval shape).

▲ Section references – Neville

Are they contagious?

  • No, canker sores are neither contagious nor infectious.

Where do canker sores form?

They characteristically only form on the “loose” (movable) tissues of the mouth, meaning those areas where the skin is not tightly bound to the bone underneath. These locations generally involve the “nonkeratinized” (softer, less tough) tissues of the mouth.

Location, location, location.

An important aspect of canker sore identification is based on the fact that they characteristically only form in certain parts of the mouth. These locations are, listed here in order of locations/tissues most affected:

Where canker sores usually form.

The ulcerations form on the “loose” tissues of the mouth.

  • The inside surface of the lips and cheeks.
  • The underside (ventral surface) of the tongue.
  • The mucobuccal fold (the deep trough where the skin of the jawbones and lips/cheeks meet).
  • The floor of the mouth.
  • The soft palate.
  • The tonsillar areas.

(Listed in order of locations/tissues most affected.)

Less common locations.

While rare, it is possible for canker sores to form on keratinized tissues. This includes the top (dorsal) surface of the tongue, the gum tissue that surrounds a person’s teeth, hard palate, or even the border of the lips (vermelion border).

When this occurs, the lesion typically involves an extension of a sore already formed on adjacent nonkeratinized tissues.

▲ Section references – Neville, Dunlap

Canker sore healing.

Healing time frames.

Canker sore (recurrent minor aphthous ulcers) characteristically heal within a certain time frame.

Therefore, what is experienced can be used to confirm lesion identification.

  • A sore will usually heal within 4 to 14 days, although some can heal in as little as 3 to 5.

    The pain associated with the lesion usually begins to subside around day 3 to 4.

  • In most cases, healing is uneventful and results in no residual scarring.
  • Any ulcer that has not healed within a 2-week time frame should be evaluated by a dentist.

    (Beyond just lesion differentiation, there is another larger kind of aphthous ulcer that characteristically does have an extended healing time frame.)

Healing appearance.

  • New skin growth (epithelialization) will begin at the edges of the ulceration and then close in from all directions as the healing process progresses.
  • The original yellow-white coloration of the pseudomembrane that covers the ulceration’s surface will transform into a more grey-white appearance as the epithelialization process advances.

    Of course, this covering will be gradually replaced at its edges by new pink skin as the size of the lesion shrinks.

  • The reddened border of the original wound will remain obvious during the early stages of the healing process. Then, as the new skin tissue matures, the border’s redness will fade. Complete healing and a normal appearance will return to the affected area within the time frame stated above.

▲ Section references – Woo, Casiglia, Scully

How often do canker sores form?

Another important aspect of canker sore identification involves correlating characteristics associated with their occurrence.

Outbreak frequency.

  • Once a person has experienced an initial outbreak, the probability of recurrence is high, although the frequency with which this takes place can be quite variable.
  • A rate of one outbreak every 1 to 3 months might be considered typical (encompassing about 50% of people who get them). 30% of sufferers deal with their presence on a monthly basis.

    That means many people will only be plagued by a few episodes a year, while others will experience nearly continuous outbreaks and therefore will never be completely free of ulcers for any extended period of time.

Incidence rates / Prevalence.

  • Most sources tend to suggest that around 20% of the general population experiences canker sores, although actual reports from studies have ranged from 5% to 66%.
  • A person’s first outbreak will typically take place between the ages of 10 and 20 years, and then decrease in frequency and severity with age.

    Lesions are most prevalent in people ages 10 to 40. 80% of those affected will experience their first lesion prior to the age of 30.

  • It’s been suggested that women are more likely to experience sores than men but not all studies confirm this fact.
  • A family (genetic) predisposition seems to exist. Children with parents who get canker sores have a 90% chance of getting them too, as compared to a 20% chance for those whose parents don’t.
  • A person’s risk seems to be unrelated to race. But people who live in North America are more likely to suffer from them, as opposed to people who live in other world-wide geographic areas.
  • Non-smokers and people in upper socioeconomic groups are more likely to experience outbreaks.

▲ Section references – Akintoye, Woo, Ship, Ship, Chavan, Neville

What are “major aphthous ulcers”?

Canker sores like we have described above are formally termed “recurrent minor aphthous ulcers.” They are the type of canker lesion experienced by 80% of sufferers.

Beyond these “minor” lesions, there’s another type of aphthous ulcer referred to as “major aphthae” or Sutton’s ulcers. And in comparison to the minor variety, they are large, deep ulcerations whose healing is characteristically slower and more painful.

  • Unlike minor aphthae, the major kind forms on all types of oral tissues (both keratinized and nonkeratinized tissues). They frequently form on the lips, soft palate or fauces of the throat.
  • They can approach 1/2 inch (or more) in diameter and may cause regional or even facial swelling.
  • Their healing usually takes between 10 and 40 days. However, it may take some months (even as new ulcers are forming).
  • Healing is often associated with scarring.

▲ Section references – Chavan, Neville

Update log –

03/12/2019 – Minor revision. Reference link added.

Authorship: Written by Staff Dentist

Topic Menu ▶ Canker Sores / Aphthous Ulcers.

  • Canker sore basics –
    • What are they? / What causes them? – Risk factors and outbreak triggers.
    • How to identify canker sores. – Lesion characteristics, Locations, Pictures.
    • Canker sores vs. Herpes lesions – How to tell them apart.
  • Treatments for canker sores (and why they work) –
    • Home remedy solutions.
    • Over-the-counter products.
    • Prescription medication approaches.
  • Related pages –
    • Topic: Cold Sores (Fever Blisters)

Page references sources:

Akintoye SO, et al. Recurrent aphthous stomatitis.

Casiglia J. Recurrent aphthous stomatitis: Etiology, diagnosis, and treatment.

Chavan M, et al. Recurrent aphthous stomatitis: a review.

Dunlap CL, et al. A guide to common oral lesions.

Neville BW, et al. Oral and Maxillofacial Pathology. Chapter: Allergies and Immunologic Diseases.

Scully C, et al. Oral medicine — Update for the dental practitioner Aphthous and other common ulcers.

Ship J, et al. Recurrent Aphthous Stomatitis.

Ship II. Epidemiologic aspects of recurrent aphthous ulcerations.

Woo S, et al. Recurrent Aphthous Ulcers: A Review of Diagnosis and Treatment.

All reference sources for topic Dental Crowns.

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