Oral Allergy Syndrome

Frequently Asked Questions (FAQ)

pdfASCIA PCC Oral Allergy Syndrome FAQ 202151.68 KB

Q 1:  What is Oral Allergy Syndrome (OAS)?

Oral allergy syndrome (OAS), also known as pollen food syndrome, is a type of food allergy with symptoms that usually affect the lips, mouth, tongue and throat. People with OAS find that some raw (uncooked) fresh vegetables, fruits, spices or nuts will make their lips, mouth, tongue and throat itch, tingle or swell.

Q 2: Can OAS result in severe allergic reactions (anaphylaxis)?

Yes, however this is rare. Some foods which commonly cause OAS can also cause food allergy, such as kiwi fruit or some tree nuts, and this can sometimes progress to anaphylaxis.

Q 3: Why does OAS mainly occur in people with pollen allergy?

OAS most commonly occurs in people with asthma or allergic rhinitis (hay fever) who are sensitised to inhaled tree, grass or weed pollens, which contain proteins that are similar to proteins found in foods.

Some pollen and food allergens share common allergenic proteins, which are known as cross reactive proteins. This means that in some people with pollen allergy, their immune system confuses a food protein with a pollen protein, resulting in OAS.

Pollen allergy usually develops before OAS, and OAS symptoms may be worse when there is a lot of the pollen you are allergic to in the air.

An example of plant proteins that are known to cause allergy and OAS are profilins, which are found in trees, grass and weed pollens as well as latex and many fruits and vegetables. Allergies to melons, citrus fruits, tomato, and banana or a combination of these suggest an allergy to profilins.

Q 4: Can people with OAS usually eat foods if they are cooked?

Yes. If the food is heated or cooked, the protein is usually destroyed, as the cross-reactive proteins in pollens and foods are often fragile. Ways to reduce OAS symptoms include:

  • Avoiding the offending food in their raw, uncooked form (ripe or unripe).
  • Eating heated, baked, cooked or canned vegetables or fruits.
  • Eating peeled vegetables or fruits, as the OAS-causing protein is often found in the skin of the produce.

Q 5: How is OAS diagnosed?

In people with pollen allergy, itching or tingling in the mouth after eating fresh fruit or vegetables is usually enough to suspect OAS. Diagnosis of OAS may be confirmed by skin prick testing for pollens and food allergens, preferably using fresh food for skin prick testing.

Q 6: Where can further information and support be obtained?

© ASCIA 2021

Content updated September 2021

For more information go to www.allergy.org.au/patients/food-other-adverse-reactions

To support allergy and immunology research go to www.allergyimmunology.org.au

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

Mod ASCIA Member
Donate to AIFA
go to NAC website

ASCIA is the peak professional body of clinical immunology and allergy in Australia and New Zealand
ASCIA promotes and advances the study and knowledge of allergy and other immune diseases

Quick Links


ASCIA is a registered trademark of the Australasian Society of Clinical Immunology and Allergy. All content is subject to copyright for the Australasian Society of Clinical Immunology and Allergy. Read more...

The content for the website is developed and approved by ASCIA Committee and ASCIA Working Party Members. Read more...

Disclaimer I Privacy

The ASCIA website is intended for use by ASCIA members, health professionals and the general public. The content provided is for education, communication and information purposes only and is not intended to replace or constitute medical advice or treatments. Read more...

ASCIA respects your privacy. Read our privacy policy here...

Sponsors | Advertising

ASCIA does not endorse products from sponsoring organisations, nor is it influenced by sponsoring organisations with regard to the content of education programs and websites. 

The ASCIA website does not accept advertising. Any link to a third-party website does not imply any endorsement by ASCIA.

Information Partner

Official Information Partner of Healthdirect Australia