Oral allergy syndrome

By Marina Zietsman

About a week ago I bit into a succulent strawberry, and sadly I won’t be able to enjoy one again. The onslaught was immediate and brutal. A quick Google search told me something I didn’t know: oral allergy syndrome (OAS).

What is it?

The American Academy of Allergy, Asthma and Immunology says that this reaction occurs because the proteins found in some fruits and vegetables are very similar to those found in pollen. These proteins can confuse the immune system and cause an allergic reaction or make existing symptoms worse. This means that should you have a pollen allergy to grass, weeds or trees, you may have an allergic reaction to foods containing similar proteins to those found in the pollen.

Prof Robin Green, a paediatric pulmonologist at the Department of Paediatrics and Child Health at the University of Pretoria and the chairman of the Allergy Society of South Africa says: “The patient has previously been exposed to the pollen allergen (protein) via the respiratory tract (the nose and lungs). These allergens are usually called Class II allergens, because they evoke a reaction to food, but not via the gastrointestinal tract. It is also more common for OAS to occur in adults or older children.”

Spot the symptoms

Dr Marinda McDonald, a GP in private practice in Joburg, with a special interest in allergies, says, “This allergic phenomenon does not generally progress to give a more serious reaction. There are however some cases where it does cause a runny nose, itchy eyes and, very rarely, anaphylaxis (a severe generalised allergic reaction).” Other signs of existing OAS include itching mouth, palate, ears and throat; a tingling in the mouth, palate or throat; watering eyes and sneezing; swelling of the lips, mouth, tongue, face or throat (very rare); some body parts may even itch when handling the raw fruit or vegetable; existing eczema might flare up; and a sensation of the throat tightening.

Managing OAS

“The reactions to the food normally occur in its raw (uncooked) state. Thus, once the food is cooked or processed, it can usually be eaten. Peeling the food can also help to remove the offending allergen,” says Green. He adds that it is important that you ascertain whether all or only some of the cross-reacting foods in a specific group cause a reaction for you individually; you may be able to eat some of the other fruits and vegetables in the group and so not deprive yourself of essential nutrients. McDonald says, “A healthcare professional who has knowledge of allergies can evaluate the risk of the reaction involved. A good clinical history by an experienced doctor is also advised.” Antihistamines might offer some relief, says McDonald, but in severe cases, seek medical help fast. “OAS is a lifelong burden and, at this stage, is not curable,” says Green. “It’s probably best to simply avoid foods that cause your OAS.”

The main offenders

If you are allergic to the following, you may develop or have OAS when eating these fruits and vegetables:

• Birch pollen – apple, raw potato, carrot, celery, hazelnut, pear, peach, plum and cherry
• Mugwort pollen – celery, apple, peanut, kiwi fruit, carrot, parsley and spices (fennel, coriander, aniseed, cumin)
• Ragweed pollen – melons (watermelon, cantaloupe, honeydew) and banana
• Latex – avocado, kiwi fruit, chestnut, papaya and banana

Courtesy of the World Allergy Organization
*Note: In South Africa there are other pollens that can cause a reaction.

• This article was originally published in Child Magazine – click here to read the original version.
• We’re sharing this article to raise awareness of allergies and the treatment options that are available for it. This article should by no means be used, or viewed, as a primary source for medical advice – please arrange for a personal consultation with your medical practitioner before making any decisions that could affect the wellbeing of you or your loved ones. Read our medical disclaimer for more information.