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Author: Vanessa Ngan, Staff Writer, 2003. Updated by A/Prof Amanda Oakley, Chief Editor, January 2016. Revised April 2021
An aphthous ulcer is painful punched-out sore that forms on oral or genital mucous membranes. They are also called aphthae, aphthosis, aphthous stomatitis and canker sores.
Anyone can get an aphthous ulcer; 20% of the population have one or more, at least occasionally. They usually first appear in childhood or adolescence, and more commonly affect females than males.
Interestingly, smoking may be protective against aphthae, even though smoking makes many oral and skin conditions worse.
The exact reason why aphthous ulcer develops is not yet clearly defined. Approximately 40% of people who get aphthous ulcers have a family history of aphthous ulcer. Current thinking is that the immune system is disturbed by some external factor and reacts abnormally against a protein in mucosal tissue.
Factors that seem to trigger outbreaks of ulcers include:
An aphthous ulcer is typically a recurrent round or oval sore or ulcer inside the mouth on an area where the skin is not tightly bound to the underlying bone, such as on the inside of the lips and cheeks or underneath the tongue. Aphthous ulcers can also affect the genitalia in males and females.
Recurrent aphthous ulcer usually begins as a round yellowish elevated spot surrounded by a red halo. This then breaks down into a punched-out ulcer, which is covered with a loosely attached white, yellow or greyish membrane. Surrounding tissue is healthy and unaffected. The ulcer can be painful, particularly if irritated by movement or eating certain types of food such as citrus fruit.
People may experience a single ulcer or multiple ulcers. Multiple ulcers tend to be widely distributed throughout a person's mouth.
Aphthous ulceration is classified into three types.
Most people affected by occasional minor aphthous ulceration do not require tests. They are undertaken if there are recurrent attacks of multiple or severe oral ulcers or complex aphthosis.
Blood tests may include:
Other causes of mouth ulcer should be considered, including:
There is no cure for an aphthous ulcer. The main goal of treatment is to lessen pain and discomfort and promote healing.
Topical prescription medicines include:
In severe cases, particularly if there are systemic symptoms, anti-inflammatory oral medications may be considered (off-label use):
Recurrent aphthous ulcers are mostly a minor nuisance, but they are associated with significant health problems in some people.
Most recurrent minor aphthous ulcers heal within 1–2 weeks without any treatment.
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