Oral allergy syndrome(OAS) is a type of food allergy. People with OAS are sensitive to specific types of pollen as well as the foods related to those pollens. OAS is sometimes also called Pollen Food Allergy Syndrome.
What is Oral Allergy Syndrome?
Most people are familiar withcommon food allergiesto things like peanuts, shellfish, tree nuts, etc. However, it is also possible to have less common allergies to things likecitrusorcelery.
Some foods contain proteins that are similar in structure to these inhaled allergens. This causes people with OAS to have food allergy symptoms when they consume those foods. This is a process known as cross-reactivity.
Cross-reactivity has been documented between birch pollen, mugwort pollen, grass pollens, ragweed, and Timothy grass with a variety of fruits, legumes, grains, nuts, seeds, vegetables, herbs, and spices.
A List of Foods That Can Trigger OAS
Here are some of the most common food triggers of OAS:
Apples
About 50% to 75% of people with an allergy to birch pollen andmugwortpollen also react to rawappledue to OAS.
Symptoms usually appear in the mouth and can occur within five minutes of eating an apple. For most people, the symptoms will occur within 30 minutes.
Symptoms tend to resolve when you stop eating the apple. It is also possible to have a more severe reaction, such as throat swelling. This can cause breathing difficulty.
Citrus
An allergy to citrus may happen when you eat one or more of the following fruits:
Reactions can range from an itchy mouth to full-fledgedanaphylaxis.Anaphylaxis is a life-threatening allergic reaction.
There is cross-reactivity between different citrus fruits. This means allergy to one citrus fruit increases the likelihood of allergy to another. Some pollens that may cross-react with citrus due to their similar protein make-up include:
Bananas
Allergicreactions to bananavary widely and may include:
Symptoms are most closely related to oral allergy syndrome and are localized in the mouth. In most cases, they begin within minutes of eating the fruit.
Cross-reactivity with ragweed is known to play a role in allergic reactions to bananas.
Spices
Corianderis in the family ofspicesthat includes:
All of these spices have been associated with allergic reactions.Cinnamon, saffron, and mustard also have been noted for causing reactions.
Across the globe, spices have become some of the most common food allergens. Cross-reactivity is commonly due to:
The main symptom is itching in the mouth.
Some spices, including oregano, thyme, coriander, caraway seed,cumin, and cayenne pepper, have been associated with an anaphylactic reaction. This is extremely rare, however.
Celery
Celery allergies are relatively common. They may be due to cross-reactivity to birch pollen and mugwort pollen, as well as grass pollens and Timothy grass. According to some research, 30% to 40% of allergic individuals are sensitized to celery.
The most common symptoms of a celery allergy include itching and swelling in and around the mouth. Occasionally, there can be a whole body response, sometimes leading to anaphylaxis.
Coconut
Coconut allergyis very rare.The FDAclassifies coconut as a tree nut for the purposes of ingredient labeling and consumer protection. Coconut is not a tree nut, however. Most people with a tree nut allergy can safely eat coconut.
Few people have a true coconut allergy, but they do exist. Symptoms include an itchy mouth and, extremely rarely, anaphylaxis. Products such as lotions and soaps containing coconut may causecontact dermatitisin some people.
Latex
Latex is produced from the sap of the rubber tree. The sap contains proteins that are similar to those found in other foods, especially fruit.
Between 30% and 50% of those with a natural rubber latex allergy are sensitized to these other foods.This is called latex-fruit syndrome. In people with this condition, eating these foods can cause allergy symptoms.
With latex-fruit syndrome, it’s most common to see cross-reactivity with:
Sensitivity to various other foods has been recorded as well.
If you are allergic to latex and have had a reaction to a food, you should avoid that food. If there is doubt, you may need to do an oral challenge test of the food under the supervision of a healthcare provider.
Symptoms of Oral Allergy Syndrome
Symptoms of OAS usually appear in the mouth. It is uncommon for them to appear elsewhere or to progress to anaphylaxis, though it can happen. Typically, symptoms include:
Symptoms of OAS usually disappear on their own and do not require treatment. This typically happens as soon as you stop eating the food.
People with OAS have a low risk of anaphylactic shock, but it can happen. Watch out for symptoms like trouble breathing, swollen throat, flushing, itchy skin, and anxiety or confusion. If any of these symptoms occur, seek medical care at once.
How Long Do Allergic Reactions Last?
How is Oral Allergy Syndrome Diagnosed?
OAS can usually be diagnosed based on your symptoms and medical history. Your healthcare provider may also want to do a skin prick test or an oral food challenge.
A skin prick test involves introducing an allergen into a small prick on your skin. If you are allergic, you will develop a reaction at the site.
During an oral food challenge, you will eat the food in the presence of your healthcare provider, who will assess your symptoms and decide if the food might be dangerous for you.
Treatments for Oral Allergy Syndrome
Because it is possible for OAS to progress to a more severe allergic reaction, your healthcare provider will advise you to avoid eating foods that cause even a mild reaction.
You may be able to eat these foods if they are cooked, but talk to your healthcare provider first. Either way, you will need to pay close attention to your symptoms. If you have an allergic reaction that spreads beyond your mouth, it could put you at risk for anaphylaxis. If this is the case, you may need to carry an EpiPen (epinephrine) in case you have a severe allergic reaction.
Summary
Oral allergy syndrome is a reaction to proteins in foods that are similar to those found in certain pollens. If you are allergic to common pollens like grass, mugwort, birch, or ragweed, you may also develop mild food allergies.
OAS may cause allergic symptoms in your mouth when you eat things like citrus or bananas, legumes, nuts, seeds, and vegetables such as celery. Usually, these symptoms go away without treatment. If they progress beyond your mouth, however, they can put you at risk for anaphylaxis. Seek emergency care if you have swelling in your throat or trouble breathing after eating fruit or any other food.
A Word From Verywell
If you have a respiratory allergy to common pollens, you should be aware of the possibility of oral allergy syndrome.
Talk to your healthcare provider if you’ve ever experienced symptoms after eating one of these potentially cross-reactive foods.
Frequently Asked Questions
Several tests may be used to diagnose OAS, including a skin prick test, a blood test, and an oral food challenge.
Yes. High temperatures break down the proteins responsible for OAS. Other strategies are to eat the food in canned form or to peel foods that can be peeled. This is because the proteins responsible for allergies are often concentrated in the skin.
Yes. In fact, research has shown that food allergies are on the rise in both adults and children and that oral allergy syndrome is the most common form of adult-onset food allergy. People may develop allergies to foods they could previously eat without symptoms.
Unless you have known allergies to other foods, you should be able to consume anything other than the foods that cause an allergic reaction. With OAS, the important thing is to avoid those foods that cause symptoms.
17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Asthma, Allergy & Immunology.Oral allergy syndrome (OAS).
American College of Allergy, Asthma & Immunology.Pollen food allergy syndrome.
Sussman G, Sussman A, Sussman D.Oral allergy syndrome.Can Med Assoc J. 2010;182(11):1210-1211. doi:10.1503/cmaj.090314
Iorio R, Del Duca S, Calamelli E et al.Citrus allergy from pollen to clinical symptoms.PLoS ONE. 2013;8(1):e53680. doi:10.1371/journal.pone.0053680
Anaphylaxis Campaign.Banana.
Popescu F.Cross-reactivity between aeroallergens and food allergens.World J Methodol. 2015;5(2):31. doi:10.5662/wjm.v5.i2.31
American Academy of Allergy Asthma & Immunology.Can spices cause allergic reactions?
The University of Manchester.Celery.
Treudler R, Simon JC.Pollen-related food allergy: an update.Allergo J Int.2017;26:273–282. doi:10.1007/s40629-017-0022-2
Anagnostou K.Coconut allergy revisited.Children. 2017;4(10):85. doi:10.3390/children4100085
American Academy of Asthma Allergy & Immunology.Coconut contact urticaria and specific IGE.
Calamelli E, Piccinno V, Giannetti A, Ricci G, Pession A.Latex-fruit syndrome and degree of severity of natural rubber latex allergy: Is there a link?Clin Transl Allergy. 2011;1(S1). doi:10.1186/2045-7022-1-s1-o18
Doenhoff M, El-Faham M, Liddell S, et al.Cross-reactivity between schistosoma mansoni antigens and the latex allergen hev b 7: Putative implication of cross-reactive carbohydrate determinants (CCDs).PLoS ONE. 2016;11(7):e0159542. doi:10.1371/journal.pone.0159542
Hussein H, Mensah RK, Brown RS.Diagnosis and management of oral allergy syndrome, the itchy tongue allergic reaction.Compend Contin Educ Dent. 2019;40(8):502-506.
American College of Asthma, Allergy & Immunology.Anaphylaxis.
Kivity S.Adult-onset food allergy.Isr Med Assoc J. 2012;14(1):70-2.
Joneja JV. The Health Professional’s Guide to Food Allergies and Intolerances.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
