Symptoms of canker sores

Canker sores are small mouth ulcers that can cause great deal of pain and discomfort. They are not cancerous and are usually associated with trauma or injury to the inner linings of the mouth called the mucosa that gets infected by bacterial invading the breach in the protective layers.

What is a canker sore?

A typical canker sore is a small ulcer within the mouth. It is commonly noted at the base of the gums, the insides of the cheeks, the soft palate (back part of the roof of the mouth), over the tongue, inside the throat or on the insides of the lips.

What do the lesions look like?

The lesions appear white or yellowish in color and have a cheesy base that signifies the ulcer. There is a raised red edge that may be swollen.

There may be a single localized sore or numerous sores in the mouth.

How many canker sores occur together?

Commonly 2 to 3 canker sores appear at one instance. However, in some individuals there may be 10 to 15 ulcers at a particular attack.

How do canker sores begin?

The sores begin as red spots or bump and go on to develop into an open ulcer. The canker sores are preceded by tingling or burning for a day before they appear.

How big are canker sores?

The sore is usually a small one with less than 1/8 to ¼ inches in diameter. Those that are major ulcers may be 1/2 inches in diameter.

Sores are most often roughly oval in shape. The whole lesion is excruciatingly painful especially the initial 7 to 10 days making it difficult to eat or speak.

Healing of canker sores

The sore may turn grey just as it begins to heal. Some patients may have other symptoms like fever, general feeling of unwell and swollen lymph nodes.

The pain recedes in a week or 10 days and the ulcer takes around 1 to 3 weeks to heal completely. Large ulcers can take longer to heal.

Inheritance of canker sores

Around 40% of the patients with canker sores have someone in their family with the condition as this condition may be inherited. Canker sores however do not spread on contact and are not contagious.

Recurrence of canker sores

In some individuals the sores may recur frequently. Attacks may vary from one sore every 2 or 3 months or even continuous presence of canker sores at various locations within the mouth.

Recurrence at the same area may indicate a repeated trauma with an ill-fitting denture or with a sharp edge of a tooth.

Therapy for canker sores

In most cases the canker sores heal without any therapy. However, since they make intake of food and nutrition difficult, these factors need to be kept in mind. Especially in children with canker sores nutritional maintenance is important.

Canker sores and more serious pathologies

Duration of the canker sore is important as longer lasting sores may be indicative of more serious pathologies like oral cancers. History of smoking, chewing tobacco and alcohol use is also important in these cases.

In addition, if there are features of fatigue, abdominal pain, fever and loss of body weight and appetite over a period of time a more serious diagnosis is considered and the patient is evaluated. Eye discomfort, rashes or sores over other parts of the body also indicate other underlying pathologies.

Three types of canker sore

Canker sores may be of three basic types:

  • Minor Aphthous Stomatitis

This is seen in more than 80% cases of canker sores. The sores are less than a diameter in size. These sores take around a week to heal completely. There is no resultant scarring after the sores have healed.

  • Major Aphthous Stomatitis

This is a more serious form of canker sores. It affects around 15% of all sufferers. These sores often last two weeks or more. They are usually over 1cm in diameter. They can be extremely painful and may leave behind scars after healing.

  • Herpetiform Aphthous Stomatitis

This occurs in less than 5% of the sufferers with canker sores. Sufferers usually get very small ulcers that may be less than a millimetre in diameters in clusters that merge to form larger ulcers. These take a week or so to heal completely. (1-7)

Further Reading

Last Updated: May 27, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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