What is oral allergy syndrome?

© Rebel_350D (Flickr) leaf
© Rebel_350D (Flickr)

Types of OAS:
There are two types of OAS: Pollen-related OAS and Latex-related OAS. Pollen-related OAS is the commonest form of pollen allergy e.g. birch pollen allergy. Latex-related OAS occurs due to similar proteins in latex and raw fruits.

Causes:
The following mix of pollen, fruits and pollens can cause oral allergy:
1. Birch (tree): almond, apples, peaches, cherries, pears, nectarine, kiwi, apricot, plum, walnut, hazelnut, potatoes, carrots, celery, parsnip.
2. Grasses (including rye): tomatoes, potatoes, peaches, wheat, peanut, melon, watermelon.

3. Mugwort (weed): celery, carrots, spices (coriander, cumin, aniseed), melons, bananas, celery, carrot. 4. Ragweed (weed): melons (watermelon, cantaloupe, honeydew), bananas, cucumbers, celery, carrots, spices, zucchini.
5. Latex-related OAS (rubber latex): avocado, banana, chestnut, kiwi, raw tomato, carrot, celery and potato, almond, fig, peach, pear, plum, mango, melon.

Symptoms:
Symptoms of OAS generally include redness, swelling, itching, burning on all or part of lips, mouth and/or throat. Sometimes, there is an occurrence of rash or blisters on or around the affected area, stomach pain, heartburn, nausea or vomiting. In some cases if symptoms (breathing problems) are overlooked asthma or rhinitis may occur.

Diagnosis:
Diagnosis is done using a ‘prick-prick’ procedure to test the skin for detecting OAS. A skin testing needle is first inserted into fresh fruits or vegetables and then used to prick the skin of the effected patient. If the outcome of the prick is a reaction, then the skin test is considered positive.

Treatment:
The first step is to rinse the mouth with plain water and take a dose of antihistamine. If it gets worse, refer to an allergy specialist. Sometimes allergy shots are administered to cross-reacting pollens to decrease or eradicate the symptoms of OAS. Immunotherapy (desensitization) can also be used to reduce or eliminate the symptoms of OAS (though it has not been completely established).

Wear masks or gloves while cooking to prevent self and others from getting infected. The best way is to avoid fresh/raw foods which cause the reaction and have them only in baked, cooked or processed form.