Canker sores

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Canker sore

Canker sore (aphthous ulcer)

Canker sores

Alternative Names:

Aphthous ulcer; Ulcer - aphthous
Symptoms:

A burning or tingling sensation before other symptoms develop (warning symptom)
Skin lesion on mucous membranes of the mouth
- Begins as a red spot or bump
- Then develops into an open ulcer
  - Usually small, 1-2 mm to 1 cm
  - Occasionally larger than 1 cm
  - Single or clusters, often appears in groups (crops)
- Painful
- Center appears white or yellow with fibrous texture
- Halo border is bright red (a red halo may not always be present)
- May have gray membrane just prior to healing

Less common symptoms, which may appear at the time of the canker but may or may not be related, include:

Fever
General discomfort or uneasiness (malaise)
Swollen lymph nodes

Signs and tests:

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A diagnosis is based on the distinctive appearance of the lesion. If canker sores persist or continue to return, a health care provider or dentist should be consulted to rule out other causes of mouth ulcers. (These include erythema multiforme, drug allergies, herpes infection, pemphigus, pemphigoid, bullous lichen planus, and other disorders.)

Squamous cell carcinoma may first appear as a mouth ulcer that does not heal, but this is rare. A relatively new ulcer-like condition is hairy leukoplakia, a condition that occurs with HIV infection and may be mistaken for the common canker.

A skin lesion biopsy may be used to differentiate a canker sore from other causes of mouth ulcers.