Canker Sores: 5 Causes and 10 Treatments to Keep in Mind

usually take the form of small yet painful swellings in the mouth. Also known as aphthous ulcers, they seemingly appear out of nowhere, usually during a person’s teen or young adult years. In truth, canker sores have multiple known causes — and the same goes for treatment options. 

Symptoms of

As the most common type of mouth ulcers, reportedly develop in about 10 percent of the population, with men being less likely to get them than women. Symptoms of these open sores include: 

  • A prickling feeling in the mouth that typically lasts for several hours 
  • Tiny, red-edged sores in the mouth (can be yellow, white, or grey)
  • One or more aching sores in the mouth

Furthermore, the more serious cases can have the following symptoms as well:

  • Fever
  • Exhaustion 
  • Swelling of lymph nodes

Canker Sore Minor Cases: Causes and Risk Factors

While are relatively common among people around the world, the exact causes of the majority of them remain elusive. However, extensive research continues to this day to determine possible causes and risk factors, some of which you can find below:

1. Tissue damage

Accidentally biting your inner cheek can easily damage the moist soft tissues and develop into canker sores. Sometimes, this happens while chewing food hard and fast — and the tissue damage becomes more severe if you have jagged teeth. Any sharp tools or ill-fitting dentures can also easily injure your inner cheeks.

2. Allergies

Allergies can cause gastrointestinal symptoms like rhinitis and vomiting. Notably, are also periodically associated with allergies. An adult can have a 10-year case of frequent canker sores and get rid of them upon avoiding food allergens like nuts and chocolate. 

Fruits and vegetables like oranges, limes, carrots, and broccoli have citric acid, which is linked to aphthous ulcers. One instance of citric acid directly interacting with the inner lining of the mouth led to a canker sore the following day. Consequently, researchers associate acetic acid (found in vinegar) with mouth ulcers.

Milk is one of the most common culprits among food items. A study in 2017 observed two young people who had recurring instances of canker sores for many years. They stopped developing more canker sores after adopting a diet free of cow’s milk protein (CMP). Moreover, the sores reappeared only when one of the patients intermittently consumed food items with CMP.

People who are sensitive to sodium lauryl sulfate (SLS) should check the toothpaste and mouthwash products they use since the ingredient may contribute to canker sores. On the bright side, they can have fewer sores if they switch to SLS-free alternatives.

3. Nonsteroidal anti-inflammatory drugs (NSAIDs)

NSAIDs include aspirin, naproxen, and ibuprofen. They alleviate inflammation and body pain. Whether you are getting over-the-counter or prescription NSAIDs, you should take utmost caution since the drugs still have their risks. Getting excessive doses and prolonged use can negatively affect your health.

Problems in the gastrointestinal tract, which includes the oral cavity, may arise from the use of NSAIDs. The inside of the mouth has a damp lining known as the mucous membrane or mucosa. NSAIDs weaken its defensive strength.

Likewise, the drugs hamper the mucosa’s ability to repair its damaged sections that are made up of soft tissues. In other words, NSAIDs and tissue damage are related to one another. If you have taken ibuprofen before biting your tongue or the inside of your cheek, the degree of injury and the recovery period of injured tissues may be slower than normal.

4. Helicobacter pylori

This bacterium is commonly located in the stomach but is also present in the oral cavity. It is good to have against chronic acid reflux. However, it can make people more susceptible to stomach and peptic ulcer disease.

Helicobacter pylori may contribute to repeated instances of canker sores, which is known as recurrent aphthous stomatitis (RAS). One study noted that people who had both H. pylori and RAS developed remarkably fewer canker sores during a six-month timeframe after undergoing H. pylori eradication therapy.

Similarly, a statistical analysis of seven studies about the relationship between H. pylori and RAS had the same conclusion: The presence of this bacterium was positively correlated to RAS, and that eliminating H. pylori in the stomach might alleviate RAS symptoms and possibly prevent more canker sores.

5. Stress

One trial study featuring 50 participants revealed that levels of psychological stress were higher among the patients who currently had canker sores than those who had no RAS. Researchers indicated that stress may contribute to the appearance of canker sores, but it is likely to be a factor rather than the main cause.

Since psychological stress is one of the usual trigger factors of the appearance and development of canker sores, another study looked into anxiety and depression. People who have a history of canker sores were more prone to increased levels of stress and than those with no RAS.

Lastly, stressful events in life are remarkably linked to the appearance of canker sores. A person who experiences a stressful event is nearly three times likelier to have RAS. Furthermore, psychological or mental stressors are more of a factor in the onset of canker sores than physical stressors. However, stressful life events seemingly had no significant relation to how long the canker sores would last. 

Canker Sore Major and Complex Cases: Causes and Risk Factors

Canker sores characterized by severe pain, bigger ulcer sizes, and longer durations (reaching up to six weeks) are called complex or major cases. Apart from the more noticeable swellings, the accompanying pain affects your ability to eat and drink. The causes and risk factors are:

1. Crohn’s disease

About one in 10 people develop canker sores as a symptom of Crohn’s disease. Interestingly, the sores sometimes appear before symptoms in the intestinal area. 

Oral ulcers may appear among people with inflammatory bowel disease because of deficiencies in iron, B12, or other hematinic nutrients. Another possible reason is the swelling of any of the hundreds of minor salivary glands in the mouth.

2. Compromised immune system 

People with canker sores may have an immunological imbalance. Problems with the immune system are known as autoinflammatory diseases. Cyclic neutropenia and PFAPA (periodic fever, aphthous stomatitis, pharyngitis, cervical adenitis) syndrome may be present in the individual if they experience canker sores and recurrent or unabating fever.

Parents should be informed about PFAPA syndrome or Marshall syndrome because it is the likeliest to occur in children compared to other fever syndromes. Apart from canker sores, it is often accompanied by abdominal pain — and the fever lasts for a few days and reappears every one to two months.

If a child has canker sores, gum disease, and fever that remains for several days and happens every three weeks, they should be taken to a dentist or a dermatologist to check for cyclic neutropenia. 

3. Behcet’s syndrome

Some diseases are significantly associated with RAS. For one, Behcet’s syndrome is a disorder that affects several parts of the body. One of its main characteristics is the appearance of major canker sores. There are also incidents where groups of tiny canker sores eventually combine into bigger ones.


The HIV (human immunodeficiency virus) disease is linked to canker sores. People with HIV tend to experience longer-lasting and more painful RAS. Research suggests that these oral might be connected to comparable sores in other body parts like the rectum and genitals. 

On the other hand, there is no consensus on how related HIV is to the frequency of canker sores. They typically appear in AIDS-infected patients whose WBC (white blood cell) count drops below a particular threshold. Sometimes, a person develops mouth sores at the early stage when their HIV infection is just taking form.

5. Nutritional deficiencies

A lack of vitamins and minerals can spell trouble. The portion of people with RAS who have nutritional deficiencies ranges from 5 to 10 percent. Minerals like folate, iron, and zinc are related to canker sores the most.

Aside from injury repair and growth, zinc is also important for the body’s immune function, especially since it is fundamental to the growth of immune cells. People deprived of zinc for just a little over one month may already get canker sores.

Several B vitamins like B1 and B6 are associated with RAS — and the same goes for vitamin D. Like zinc, vitamin D is crucial to the immune system. People with canker sores have significantly lower serum levels of vitamin D than those without.

Canker Sore Treatments

The good news is that most canker sores generally go away within a couple of weeks without any need for treatment. Moreover, they tend to be less painful after just a few days. However, consider going to your doctor if you experience any of the following:

  • Get bigger and more numerous canker sores than usual
  • Have canker sores that persist longer than a week or two
  • Continue to feel severe pain due to the canker sores
  • Develop fever while also having canker sores

A qualified health professional may prescribe any of the following treatments:

1. Dietary supplements

Particular nutritional supplements may help treat canker sores depending on the vitamin or mineral deficiency identified. Not all kinds of supplementation will provide significant benefits to all who take them, but taking oral vitamin B12 supplements can help people with canker sores whether they have vitamin B12 deficiencies or not.

2. Mouthwash

Oral rinse products are great for treating canker sore. Prescription-only mouthwash usually has substances to alleviate pain and reduce inflammation. In contrast, be wary of mouth rinse that has alcohol since it can worsen the pain instead.

3. Topical medication

The aforementioned lidocaine anesthetic does not just come in liquid form for mouthwash products. Lidocaine ointments and gels can also be bought at pharmacies and supermarkets, but such variants containing choline salicylate should not be given to people under 16 years old.

Amlexanox is a topical paste that people can use as soon as they notice canker sore symptoms. Daily application is maxed at four times, typically conducted after meals and before sleep. However, people with immunological disorders should refrain from using this medication. 

Lastly, beclomethasone is a steroid medication that can come in the form of a topical aerosol spray. It does not permanently stop new sores from appearing, but it is effective in reducing the degree of pain and frequency of canker sores.

4. Cauterization

This method involves burning the affected area to remove the canker sore and prevent future infection. One way is laser therapy, which can burn oral without causing pain to the patient. The sores heal in as early as two days instead of weeks. New canker sores cannot appear in the same area because the lasers target the nerve ending.

Chemical agents are also suitable for cauterizing canker sores. Doctors can prescribe the topical liquid Debacterol, which only requires one application and can alleviate pain from the aphthous within seconds. Significant reductions in canker sore symptoms become apparent within three days.

Similarly, silver nitrate is a chemical agent that needs a single application for long-term pain alleviation. Discomfort from canker sores is diminished just a day after use. However, the cauterizing agent does not notably affect the healing period of canker sores. 

Canker Sore Home Treatment

There are several easily obtainable or readily available options if you cannot immediately go to your doctor:

1. Honey

The antibacterial and therapeutic properties of natural honey make it an affordable and non-irritable remedy for canker sores. Individuals may feel much less pain and see a size reduction of ulcers three days after application.

2. Milk of magnesia

Use a cotton swab to apply milk of magnesia directly on the canker sore up to four times a day. For an improved (but still temporary) pain alleviation, use it after taking an oral rinse that contains hydrogen peroxide.

3. Ice

Rather than ice cubes, use the smaller-sized ice chips on canker sores. Avoid chewing the ice. Simply let the ice chips dissolve in the mouth to help against inflammation and pain.

4. Topical medication

Over-the-counter topical medication like gels and creams can still speed up the healing process and reduce pain.

5. Mouth rinse

People can either choose to rinse with salt or baking soda. To create the first one, dissolve a teaspoon of salt in half a cup of warm water. Use the solution for up to 30 seconds. You may do this repeatedly each day, but wait a few hours before another application. The canker sores will dry quicker than normal, but remember that the salt rinse itself may be quite painful.

The alternative is the baking soda mouthwash, which can be made by dissolving a teaspoon of it in half a cup of warm water. Both homemade oral remedies can be incredibly salty, so try not to swallow either solution.