Mouth Ulcer (Canker Sore): Everything You Need to Know
Medically reviewed by Brian T. Luong, DMDMedically reviewed by Brian T. Luong, DMD
A mouth ulcer, also known as a canker sore, is an erosion of an area of tissue (mucous membrane) inside the mouth. They can vary by size and location within the mouth, such as inside the lip, on the tongue, or on the roof of the mouth.
Canker sores tend to be white or yellow and surrounded by a red area. They are painful but usually not serious, and most clear up on their own. They are not cancerous, and they are not the same as a cold sore.
Canker sores are fairly common, with about 20% of people experiencing them on a regular basis. They can happen at any age, but typically begin appearing between the ages of 10 and 20 years.
This article will discuss the types, symptoms, and causes of mouth ulcers, whether they are cancerous, the difference between mouth ulcers and cold sores, how they are diagnosed and treated, ways to find relief, the outlook for people with mouth ulcers, how to prevent them, and when to contact a healthcare provider.
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Types of Mouth Ulcers and Their Symptoms
Symptoms of mouth ulcers can vary by type. Generally, they appear on the:
Inner surface of the cheeks and lips
Upper surface of the mouth
Tongue
Base of the gums
The most common type of mouth ulcer/canker sore is aphthous ulcers. Aphthous ulcers are divided into three categories:
Minor aphthous ulceration
Major aphthous ulceration
Herpetiform aphthous ulceration
Aphthous Ulcers
Aphthous ulcers are typically found in the softer mouth lining, such as inside the lips, cheeks, sides of the tongue, floor of the mouth, roof of the mouth toward the back, and in the tonsil area. They usually resolve within 10 to 14 days, but often recur. Recurrent aphthous ulcers affect about 1 in 5 people.
Specific symptoms of aphthous ulcers depend on the type, but general symptoms include:
One or more round or oval "punched-out" sores inside the mouth
Sores that begin as a round, yellowish, elevated spot surrounded by a red "halo"
Sores then break down into a punched-out ulcer that is covered with a white, yellow, or grayish membrane, and usually surrounded by healthy tissue
Ulcers that are usually painful, especially when irritated by chewing, brushing teeth, eating certain foods (salty, spicy, sour, citrus), wearing dentures or orthodontia such as braces, and other irritants
Complex aphthous can include nearly constant ulcers, and/or oral and genital aphthous ulcers.
Less commonly, aphthous ulcers may cause fever, swollen lymph nodes, general discomfort, and/or uneasiness.
Minor Ulcers
About 85% of aphthous ulcers are recurrent minor aphthous ulcers, also called minor canker sores.
Minor canker sores are less than 10 millimeters (mm) in diameter and heal within a week or two.
Mild canker sores are typically slightly sunken, with reddish edges that are slightly raised.
They can appear as a solitary sore or in clusters of up to four to six at a time.
Major Ulcers
Major aphthous ulcers, also called major canker sores, are less common, accounting for about 10% of canker sores.
Major canker sores are large ulcers, or several ulcers that have come together to form a large ulcer, that are greater than 10 mm in diameter and have raised margins. They are often associated with fever, malaise (generally feeling unwell), and dysphagia (difficulty swallowing).
The pain from major canker sores can be stronger, and last longer than with minor canker sores. Healing time can also be longer, taking up to four weeks (sometimes longer) to resolve.
Major canker sores often leave a scar.
Herpetiform Ulceration (HU)
The term herpetiform means to resemble herpes and is used to describe clustered vesicles (small fluid-filled membrane bulges). It doesn't mean that it is associated with a herpes virus.
Herpetiform ulceration, also called herpetiform canker sores, are many pinhead-sized ulcers. They occur most often on the tongue, and typically heal within a month.
These tiny sores may merge together to form larger areas, which can cause scarring.
Herpetiform canker sores account for about 5% of canker sores.
What Causes a Mouth Ulcer?
The cause of a canker sore isn't always known. Some things that may trigger a canker sore include:
Trauma to the area (such as from dental work, biting the tongue or cheek, or brushing teeth too roughly)
Stress
Hormonal changes
Vitamin or mineral deficiencies (particularly iron, folic acid, or vitamin B12)
Constant rubbing from misaligned or sharp teeth, dentures, or braces
Burns (such as from hot food or drinks)
Irritation from strong antiseptics (like mouthwash) or sodium lauryl sulfate (an ingredient in many mouthwashes and toothpastes)
Genetics (canker sores appear to run in families)
Feeling rundown (ill, lacking sleep, etc.)
Certain food additives or food allergies
Certain medications (such as the angina medication nicorandil)
In some cases, canker sores may be associated with certain medical conditions, such as:
Inflammatory bowel disease
Cyclic neutropenia (rare blood disorder)
Celiac disease
Conditions that weaken the immune system, such as human immunodeficiency virus (HIV)
Is a Mouth Ulcer Cancerous?
Canker sores are not cancerous and they do not lead to cancer. Some types of mouth cancer can resemble canker sores.
A canker sore that isn't painful and/or doesn't heal can be a sign of mouth cancer and should be evaluated by a healthcare professional.
Mouth Ulcer vs. Cold Sore: How to Tell the Difference
Canker sores and cold sores are both mouth sores, but they are not the same condition and have several key differences.
Cold sores:
Start as blisters filled with fluid, then crust over, become a sore, and scab before going away
Are usually found outside the mouth, such as on or around the lips, chin, or nostrils, and sometimes inside the mouth
Are caused by the herpes simplex virus (usually HSV-1)
Are contagious through contact such as kissing or touching someone with cold sores, or sharing items like utensils or towels
HSV can cause fever, muscle aches, swollen neck glands, general ill feeling, and redness and swelling of the gums
Canker sores:
Are found inside the mouth, not outside
Are not contagious
Typically do not cause additional symptoms, such as fever, muscle aches, or feeling unwell
How Are Mouth Ulcers Diagnosed?
Canker sores are usually diagnosed by a visual examination from a healthcare provider or an oral health professional.
If an underlying cause of the canker sore is suspected, or the lesion may be something other than a canker sore, additional tests may be ordered, such as:
A biopsy (removing a tissue sample to be analyzed in a lab)
Blood tests (complete blood count, and to look for inflammatory conditions, or vitamin and mineral deficiencies)
Bacterial and viral swabs
Fecal calprotectin (testing a stool sample for signs of inflammatory bowel disease)
Allergy tests
How to Find Relief From a Mouth Ulcer
Canker sores usually go away without treatment, but they can be painful while they are healing.
Some strategies that may help ease discomfort from canker sores include:
Avoid irritating foods and drinks, such as chocolate, citrus, nuts, seeds, tomatoes, coffee, and foods that are spicy, salty, or rough (like potato chips).
Eat foods that are easy to chew and swallow (such as macaroni, yogurt, cottage cheese, or cream soups), or mash, blend, or puree foods to make them easier to eat.
Drink cold liquids or eat frozen foods such as Popsicles.
Put ice (wrapped in a towel or other barrier) on the sore (be careful not to leave it long enough to cause tissue damage).
Use a straw to prevent liquid from coming into contact with the ulcer.
Avoid smoking and chewing tobacco.
Keep your mouth clean.
Be gentle when brushing your teeth, and avoid the sore.
Avoid mouthwashes and toothpaste that contain sodium lauryl sulfate.
You can also try remedies and over-the-counter products such as:
Numbing medications like benzocaine products (such Anbesol, Orabase, or Orajel)
Milk of magnesia (dab a small amount on the canker sore three to four times a day)
Anti-inflammatory medications such as Advil or Motrin (ibuprofen) or Aleve (naproxen), or other pain relievers such as Tylenol (acetaminophen)
Mouth rinses with salt water, or mild alcohol-free mouthwashes
A mixture of half hydrogen peroxide, half water, applied directly to the sore with a cotton swab (followed by applying milk of magnesia) three to four times a day
Mouth rinses with a mixture of half milk of magnesia, half liquid Benadryl (diphenhydramine) allergy medicine (swish mixture around in the mouth for about one minute, then spit it out)
Medical Treatment Options
Uncommonly, canker sores may need medical treatment.
In some cases, your healthcare provider or oral health professional may prescribe:
Prescription mouthwash, such as chlorhexidine
Oral or topical corticosteroids
Immunosuppressant medication
Applying Topical Medications
When applying medications directly to the canker sore:
First, use a tissue to blot the area dry.
Apply a small amount of the medication using a cotton swab.
Avoid eating and drinking for at least 30 minutes after application to prevent the medication from being washed away.
What Is the Outlook for Someone With a Mouth Ulcer?
In most cases, minor canker sores heal within one to three weeks, and pain often goes away in a week or two. It is common for them to recur periodically.
Major canker sores can take longer to heal and often leave scarring.
For most people, recurrent aphthous ulcers are uncomfortable but not serious. In some cases, they may be associated with more serious health problems.
Rarely, canker sores can become severe (permanent, so painful they interfere greatly with eating and drinking, or involving the mucous membranes of the genitals).
There is a tendency for aphthous ulcers to gradually become less severe later in life.
How to Prevent a Mouth Ulcer
It isn't always possible to prevent canker sores, but some measures that may help lower the risk include:
Brushing gently and carefully to avoid trauma
Eating nutritious foods as part of a well-balanced eating plan
Addressing and controlling underlying health conditions
Avoiding triggers, if you know them
Practicing good oral hygiene, including regular dentist visits
When to Contact a Healthcare Provider
Contact a healthcare provider or oral health professional if:
The canker sore does not go away after two weeks.
The canker sore gets worse.
You get more than two or three canker sores a year.
You have symptoms with the canker sore, such as fever, headache, skin rash, or diarrhea.
The ulcer is interfering with normal daily activities, including eating and drinking.
You have signs of infection (such as pus draining from the area, fever, increased pain, swelling, warmth, or redness).
There are four or more ulcers.
There are ulcers and/or sores also on the outer lip.
There is an ulcer on the gum near a tooth with a toothache.
There are red, swollen, or tender gums.
There are bloody crusts on the lips.
There is a large lymph node under the jaw.
The ulcer appeared after starting a medicine.
The ulcer is different than other ones you have had before (bigger, near the back of the throat, etc.).
The ulcer bleeds or becomes more painful.
You have ulcers in areas other than inside your mouth.
You have painful, red, or swollen joints.
Summary
Mouth sores, also called canker sores, are painful, white or yellow lesions inside the mouth. Most canker sores are minor and clear up on their own within two weeks. Less commonly, they may be major (larger than 10 mm) or herpetiform (many pinhead-sized ulcers).
Canker sores don't always have a known cause, but may be triggered by factors such as trauma to the area, abrasive foods or dental products, stress, vitamin or mineral deficiencies, or some medical conditions.
Canker sores usually don't require treatment. In more severe cases, prescription topical or oral medications may be necessary.
See your healthcare provider if you have a sore you aren't sure is a canker sore, if your canker sore doesn't go away within two weeks, you have other symptoms, or you have any concerns.
Read the original article on Verywell Health.
