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What is OAS?
Oral Allergy Syndrome is a form of contact urticaria confined to the lips, the mouth, and the pharynx. By definition it does not involve other parts of the body and must be distinguished from early symptoms of a more generalised reaction such as anaphylaxis or shock.
What are the symptoms?
Symptoms include:
§ Rapid onset of itchiness (pruritus)
§ Swelling of the lips, tongue, palate and throat
These symptoms tend to resolve fairly quickly.
Who are affected?
This condition is most often seen in people who are also allergic to pollen; e.g. persons allergic to ragweed may experience these symptoms after eating melons or fruit from this family (watermelons, honeydew, cantaloupe, etc (see families)) and bananas. Persons sensitive to birch pollen may develop OAS following ingestion of carrots, raw potatoes, apples, celery, hazelnuts and kiwi fruit.
How is the diagnosis made?
Diagnosis is made from a strongly suggestive history and may require Skin Prick Testing with the implicated fruits and vegetables.
What is the treatment?
This condition can be treated effectively with antihistamines, and particularly the new long acting ones. Caution must be exercised to ensure that these symptoms remain localised and are not the onset of a more generalised reaction. Desensitisation has been useful in individuals with severe recurrent OAS.
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