What is OAS?

Have you ever eaten an apple only to find that a few minutes afterwards you begin to experience itchiness on your lips and in your mouth? Did you ever get nauseous from enjoying a tasty banana? These are both things that I have experienced. Over the years it seems that such reactions to eating certain fruits, vegetables, and nuts has become more common to me. With a bit of research I found that while I do not seem to have any actual food allergies, my symptoms are actually being caused by my seasonal allergies - a problem known in the medical field as Oral Allergy Syndrome.

Oral allergy syndrome mostly affects teens and adults, though younger children sometimes get it, too.


The proteins present in certain fruits and veggies confuse the immune system in some people who have food and/or seasonal allergies because of how similar they are to the proteins found in the pollen of those same fruits and veggies.

For example, someone who is allergic to birch tree pollen (a common cause of springtime airborne allergies) may have reactions to peaches, apples, and celery.

The cross-reactors chart below lists the correlations between specific types of seasonal allergies and OAS triggers.


  • Itchiness, tingling, or swelling of the face, mouth, lips, throat and/or tongue
  • Dizziness
  • Nausea
  • Vomiting
  • Diarrhea
  • Hives
  • Shortness of breath

*While symptoms tend to be mild and only last for a short period of time, they commonly show up right after eating, although it is possible to take up to an hour+.


When getting tested, many people find that while their allergy testing is negative for foods, they are instead positive for birch, grass, or ragweed pollen.

You may not have reactions to all of the foods associated with a specific pollen. It's possible that you may only have a problem with one or two foods. For example, you may have reactions from eating apples and pears, but be just fine with almonds and strawberries.


1. Avoid eating the fruits and vegetables that trigger your OAS symptoms, especially during the height of pollen season. But if that pear or apple just looks too good and you still really want to eat it, try peeling the skin off first since most of the proteins that you want to avoid are present in the skin.

2. Opt for canned, processed, or pasteurized foods over fresh fruit and vegetables. (Symptoms may still be present after eating dried or dehydrated fruits/veggies.)

3. Eating frozen fruits can usually lessen or eliminate your OAS symptoms. Also, try eating your fruits in a smoothie, yogurt, honey, or some other form of fruit dip that can coat the surface of the fruit, also protecting your throat and stomach from those proteins.

4. The best way to enjoy the fruits and veggies that cause your OAS symptoms would be to eat them cooked. Heat breaks down those proteins associated with the syndrome. You can do this numerous ways - grilling your food, cooking it in the oven or on the stove, or even giving it a quick zap in the microwave. But keep in mind that this does not work with all foods, like celery.


If your symptoms are making you miserable, an immunologist, often referred to as an allergist, can help develop a treatment plan to help you feel and live better.

While there is no medication for Oral Allergy Syndrome, antihistamines, epinephrine (for severe reactions) and immunotherapy are three courses of action.

Immunotherapy is a treatment used for hay fever but has had some success in people with oral allergy syndrome. Immunotherapy can be given through allergy shots or oral (by mouth) medication.

If you are at risk for anaphylaxis, (a life-threatening reaction) your doctor may prescribe an epinephrine auto-injector.

If you decide to completely avoid your trigger foods, it may be wise to speak with a dietician to make sure that you are still having a healthy and balanced diet.

Some of my OAS reaction triggers.
Created By
Yvette Shanks

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