Oral Allergy Syndrome

Oral allergy syndrome is an allergic reaction to certain proteins in fruit, vegetables and nuts.

This condition is called "oral allergy syndrome" because it usually affects the mouth and throat.

People affected with oral allergy syndrome

Oral allergy syndrome is nearly always preceded by hay fever. It also tends to occur most often in older children and adults.

It is usually associated with birch-pollen allergies but it can also affect people with allergies to the pollens of grass, ragweed (more common in North America) and mugwort (more common in Europe). These reactions can occur at any time of year but are often worse during the pollen season.

Symptoms of oral allergy syndrome

Symptoms may include

  • itching and burning of the lips, mouth and throat
  • watery itchy eyes
  • runny nose
  • sneezing

Symptoms usually develop within minutes of eating or touching the food, but occasionally occur more than an hour later.

For some people, peeling or touching the offending foods may cause a rash, itching or swelling where the food touches the skin.

More serious reactions can include hives and swelling of the mouth, pharynx and windpipe.

In rare cases, severe allergic reactions have been reported, such as

  • vomiting and diarrhea
  • bronchial asthma
  • generalized hives
  • anaphylactic shock

Reactions to fruits and vegetables associated with oral allergy syndrome

Not all reactions to fruit and vegetables are associated with oral allergy syndrome.

A variety of fruit, vegetables and their juices sometimes cause skin rashes and diarrhea, especially in young children. These include

  • apples
  • grapes
  • oranges
  • tomatoes

Strawberries occasionally cause hives.

Food involved in oral allergy syndrome

Food associated with birch, ragweed, grass and mugwort pollen are listed in the following table.

Because the allergenic proteins associated with oral allergy syndrome are usually destroyed by cooking, most reactions are caused by raw food. The main exceptions to this are celery and nuts, which may cause reactions even after being cooked.

Some plant parts, such as the skin, may be more allergenic than other parts.

The allergic characteristics of some fruit seems to decrease during storage.

Foods associated with oral allergy syndrome, which could cause anaphylactic reactions, include:

  • beans
  • celery
  • cumin
  • hazelnut
  • kiwi
  • parsley
  • white potato
Food Most Commonly Associated With Birch, Ragweed, Grass And Mugwort Pollens
Allergies to this type of Pollen May also trigger an allergic reaction to these foods
Birch Fruits: apple, apricot, cherry, kiwi, nectarine, peach, pear, plum, prune
Vegetables: anise, beans, caraway, carrot, celery, coriander, cumin, dill, fennel, green pepper, lentils, parsley, parsnips, peanut, peas, potato, tomato
Nuts: almond, hazelnut, walnut
Seeds: sunflower
Grass Fruits: kiwi, melon, orange, tomato, watermelon
Mugwort Fruits: apple, melon, watermelon
Vegetables: carrot, celery
Ragweed Fruits: banana, cantaloupe, honeydew, watermelon
Vegetables: cucumber, zucchini

Source: Zarkadas M, Scott FW, Salminen J, Ham Pong A. Common Allergenic Foods and Their Labelling in Canada - A Review. Canadian Journal Allergy & Clinical Immunology 1999; 4:118-141.