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Oral allergy syndrome

Oral allergy syndrome is also known as pollen-food syndrome. It was rare 20 years ago but is now the number one food allergy to affect adults. It usually occurs in those who have hayfever in the spring or summer and who are allergic to pollen from trees (especially birch trees), grasses or weeds.

What is oral allergy syndrome?

It's an allergic reaction in the mouth and throat after eating foods that contain proteins of a similar structure to those found in pollens from trees, grasses and weeds. The body mistakenly reacts to the food proteins, most often during the hayfever season, but oral allergy syndrome can occur all year round.

The foods involved are usually raw fruits and vegetables, and some nuts and spices.

Symptoms of oral allergy syndrome

Symptoms of oral allergy syndrome usually occur within minutes of eating the food and include itching or rashes around the mouth and lips - hence the name, oral allergy syndrome. Symptoms, which can also include mild swelling, have normally subsided within an hour.

Occasionally someone with pollen-food syndrome may have more severe symptoms which can include nausea and vomiting.

People can have hayfever for some years before they develop the symptoms of oral allergy syndrome.

Causes of oral allergy syndrome

People can be affected by a wide range of foods or just one or two. Part of the reason for the increase in cases of oral allergy syndrome may be our taste for more exotic and unusual fruit and vegetable varieties from around the world.

The most common foods which may lead to a reaction are:

  • Raw apples
  • Peaches
  • Pears
  • Plums
  • Cherries
  • Nectarine
  • Kiwi fruit
  • Strawberry
  • Carrot
  • Celery
  • Tomato
  • Soy milk (but not other soy products)
  • Hazelnuts
  • Brazil nuts
  • Almonds
  • Walnuts
  • Peanuts

Food preparation may cause reactions also, for example peeling potatoes.

Diagnosis

Testing for oral allergy syndrome is done by an allergy specialist. This involves a special skin-prick test using prepared extracts or direct testing with fresh fruit and vegetables.

If you are allergic, an itchy bump will come up within minutes but will settle down over about an hour.

Treatment and tips

There are things people can do, like rinsing their mouth to get rid of the residue of the allergens or having a warm drink to inactivate them.

If symptoms are very unpleasant you can take a dose of an antihistamine, although mild symptoms will usually settle within 30 minutes, before an antihistamine has had time to start working.

For more severe reactions you may be prescribed an adrenaline pen.

The advice from experts is not to abandon your 5-a-day but to identify the specific foods that cause the allergy and avoid them.

It's also possible that cooking can destroy the allergens that cause the reaction. Consequently, a person who has an allergic reaction to raw apples may be able to eat cooked apples. The reverse can also be true. So, a person may be able to eat raw celery but have a reaction when it's cooked.

Some people find that different varieties of fruits or vegetables can be tolerated, so just because you have a reaction to one type of apple, doesn't mean all apples will cause symptoms.

Avoid smoothies and freshly squeezed fruit or vegetable juices as they can contain a lot of the proteins which cause a reaction. UHT or long-life juices should be fine.

When preparing meals for others, if possible, get someone else to do the peeling or scrape the fruits and vegetables as particles can get in the air and cause an allergic reaction. Wearing gloves or a mask can help.

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WebMD Medical Reference

Medically Reviewed by Dr Sheena Meredith on July 22, 2016

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