Canker Sores or Fever Blisters?

Q: What is a canker sore and what are fever blisters (cold sores)?

A canker sore is an ulcer (open sore) in the mouth, appearing as either a painful white (yellow) sore surrounded by a reddish grey border could be a canker sore which is quite different than a fever blister or herpes. The medical term for canker sores are Apthous Stomatitis. These apthous ulcers are usually small (1-5 mm), appearing either solitary or as a cluster of small ulcers. They can however sometimes be larger (5-10mm).

They can occur at any age, but occur more commonly in women. Canker sores only occur inside the mouth, appearing on the movable tissue of the mouth i.e. the tongue, soft palate, cheeks and inside lining of the lips or the bottom of the gums (vestibule). It usually starts with a burning sensation, followed by a red area that ulcerates. These painful ulcers can take 1-2 weeks to heal. The sores are rarely associated with any other diseases and fever is rare.

Canker sores must not be confused with Herpes (commonly known as fever blisters or cold sores). Oral Herpes most commonly occurs outside the mouth on and around the lips and facial area. When Herpes occurs within the mouth, it will only occur on the non-movable tissue which are the gums adjacent to teeth (gingiva) and on the hard palate (roof of the mouth) Herpes ulcers are smaller than canker sores and form blisters before ulcerating. Canker sore outbreaks are common and may continue for years. Canker sores are not contagious and no need to worry about spreading them to others.

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