Mouth ulcers or canker sores are painful: Here’s how to treat them

Canker sores are mouth ulcers that can often cause unbearable pain and make it tough for you to eat or drink anything. Read on to know more
A canker sore on the inside of the cheek
Constant biting of the cheek, or misaligned teeth rubbing against the cheek can lead to canker sores. Image courtesy: Adobe Stock
Anjuri Nayar Singh Published: 8 Jun 2024, 19:03 pm IST
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A mouth sore is enough to make your appetite go for a toss, right? Canker sores are painful sores that usually appear inside your mouth, at the base of your gums. While these are not contagious, they are quite uncomfortable. Just about anything can trigger an episode of canker sores. Acidic foods or even stress can leave you with a canker sore. It becomes very difficult to eat, and even talk with canker sores, and, hence, it is important to seek treatment for them at the earliest. Read on to know more about canker sores, and how to treat them.

What are canker sores?

Canker sores, also called aphthous ulcers, are small shallow ulcers that occur in the lining of your mouth. “They measure less than a millimetre but may grow to half or 1-inch diameter too. It is not contagious and never occurs on lips,” says general physician Dr Roohi Pirzada.

Symptoms of a canker sore

There are some characteristics of a canker sore, that can help you determine a diagnosis. According to a study published by the National Institutes of Health, a canker sore is white or yellow and is small in size. It forms a red area in the mouth that is extremely painful. It also leads to a tingling sensation.

The report states that canker sores are not contagious. While the pain takes about a week to 10 days to subside, the affected area will be restored to normal in about three weeks, that’s how much time it takes for a canker sore to completely heal.

Causes of a canker sore

Some lifestyle habits can lead to the emergence of canker sores:

1. Chewing tobacco

This can cause physical trauma to the mucosal lining of your oral cavity. It can cause injury as well as irritation to your oral tissues, states a study, published in the International Journal of Dermatology. It stated that smokers reported a significantly higher chance of getting a canker sore.

2. Uneven teeth

There can be dental irritation due to a jagged tooth. This may constantly irritate the oral mucosa. A part of your mouth is constantly being rubbed against your tooth. It may also lead to biting the inside of your mouth, and cause a canker sore.

3. Weak immune system

You might have a weak immune system due to chronic illnesses or due to anti-cancer medications. According to a study published by the National Institutes of Health, a weak immune system, stress or even a chronic disease can increase the tendency to get a canker sore. New canker sores may be formed due to these conditions.

4. Vitamin deficiency

The study, mentioned above, also reported that deficiencies in iron or vitamin B can lead to the occurrence of canker sores. Vitamin B complex especially B12 deficiency is linked to mucosa deficits as well.

Other causes may include food allergies, especially while consuming sour and spicy food may break the mucosa barrier, emotional stress, digestion issues and inadequate sleep that can all lead to acid reflux in the oral cavity, as well as hormonal changes.

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A woman with a toothbrush in her hand
Regular brushing and flossing, as well as oral hygiene can help in canker sores healing faster. Image courtesy: Adobe Stock

How are canker sores and cold sores different?

Cold sores are contagious. They are fluid-filled blisters and they may burst and liquids ooze and form a crust. They usually disappear in 5 to 10 days without scarring. There may be accompanying fever, swollen lymph nodes, headache, nausea, and sore throat. However, canker sores are non-contagious, they are visible inside the oral cavity such as cheeks, soft palate or tongue. They heal without treatment but may re-appear at the same or different spot.

Forms of canker sores

1. Minor aphthous stomatitis

This is the most commonly seen canker sore and this takes about one to two weeks to heal. These present themselves as small oval-shaped sores, which are painful. You will experience a tingling sensation and eating food might be difficult.

2. Major aphthous stomatitis

These canker sores exceed one cm in diameter. They take longer, almost up to a month, to completely heal themselves. Besides a tingling sensation, you will also experience inflammation, as well as a lot of pain. It would be tough to speak as well, besides not being able to eat.

3. Heretofore aphthous stomatitis

This refers to multiple ulcers that come up from time to time. These form clusters and take up to a few weeks to heel. This also makes it tough to chew your food or talk, as well as drink liquids.

How to diagnose canker sores?

Your doctor can usually diagnose a canker sore by visual examination itself. A study, published in the Journal of Clinical And Aesthetic Dermatology, states that an investigation needs to be made regarding any trauma that the person has undergone recently, dental appliances used by the patient as well as hormonal imbalances.

The doctor may order blood tests to rule out nutritional deficiency. In severe or non-healing sores, a biopsy may help diagnose a pre-cancerous or a cancerous lesion.

How are canker sores treated?

Canker sores can heal on their own, and most of them do as well. However, a doctor can prescribe occlusive agents like benzoyl alcohol gel, cleaning agents like hydrogen peroxide 3% mixed with equal water or an anaesthetic agent like benzocaine gel, which is sure to help you feel better.

You should also maintain mouth hygiene and make sure to floss your teeth two times daily. Also, it is important to not have spicy foods when your canker sore is healing, as this will make it feel worse.

Home remedies to treat canker sores

There are some home remedies that you can try if you have a canker sore. A study, published in the Journal of International Oral Health, states that ice or even a tiny amount of milk of magnesia can help make you feel better. This can help with the pain, and heal the canker sore faster. Here are some other cures as well.

A study, published in Quintessence International, had honey applied to patients with canker sores. Honey was found to be a safe and effective home remedy to reduce pain as well as the size of the sore.

A mouth ulcer on the inner lip
Canker sores are different from cold sores, the latter happens on the lips and can be contagious. Image courtesy: Adobe Stock

How to prevent canker sores?

You need to assess the cause of the sore, and then work on that. If you are stressed, and that episode leads to canker sores, then you can look for effective ways to relieve your stress. Deep breathing, meditation or even working out may help. Avoiding spicy foods is another way of avoiding canker sores, as anything acidic can lead to their emergence. Vitamin and mineral deficiencies can also lead to these sores, and hence, supplements or dietary changes might help.

Complications of canker sores

While canker sores can heal on their own, there are times when they go out of hand, and can get dangerous. You must go to the doctor if you experience very large sores, too much pain, fever, rash, or a headache. Also, if a canker sore does not get better on its own in three weeks, then you will need to get further medical assistance.


Canker sores are yellowing sores that appear in your mouth or along your gums. They are not contagious and usually heal on their own in a few weeks. However, a fever accompanying them, or a rash needs further investigation. Canker sores happen due to eating spicy foods, stress or vitamin and mineral deficiencies. To prevent canker sores, you must determine the cause behind the sore, and rectify that.


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About the Author

Anjuri Nayar Singh has over 12 years of experience in writing for various topics including lifestyle, films, television and OTT. She also writes on art and culture, education and human interest stories. ...Read More

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