Oral Allergy Syndrome (OAS)—A Seasonal Mess?
Ahh, summer. The season of pool parties, barbecues, gardening, and outdoor adventure. For many, summer also means seasonal allergies. That’s right: runny noses, itchy eyes, and nasal congestion. In addition, it’s the season of fresh fruits and veggies! But for some, that means an itchy mouth.
If you’ve ever bitten into a raw apple, banana, or piece of celery and experienced an itchy mouth, you’re not alone. This reaction occurs because the proteins found in some raw fruits and vegetables are similar to those found in plant pollen. Your body perceives these similarly structured proteins as pollen allergens. This recognition overlap is also referred to as cross-reactivity. If you’ve experienced this reaction, you may have oral allergy syndrome (OAS). Or what Amulet’s allergist advisor Dr. John Lee calls: the most common allergy you don’t know you have.
You’re probably wondering if you’ve ever experienced OAS. The most common symptoms include itchiness or swelling of the mouth, lips, face, tongue, and throat. These symptoms typically appear right after eating raw fruits or vegetables. OAS is considered a mild form of food allergy, and only in very rare instances has OAS resulted in a more serious allergic reaction like anaphylaxis.
Let’s take a closer look at which common plant pollens most often cross-react with which fruits and vegetables:
It’s important to note OAS isn’t limited to the above chart of fruits and vegetables—certain spices, legumes (peanuts and soybeans), and nuts (almonds and hazelnuts) can bring about OAS symptoms as well.
The good news? Many people affected by OAS can eat the same fruits or vegetables when cooked! Heat alters the protein structure in the food, so the immune system no longer recognizes them as similar to pollen proteins. Peeling these fruits and vegetables before eating them can also stave off an OAS reaction, as these proteins are often concentrated in the skin. However, many allergists recommend avoiding the food in raw form altogether if it’s causing symptoms. Alternatively, consider eating canned versions of these nutritious favorites if you can’t resist them, as processing helps destroy the proteins typically involved in OAS.
If you've experienced OAS symptoms after eating a raw fruit or vegetable, you may want to consult with your healthcare provider or allergist. Because standard food allergen tests (skin prick or blood test) often come back negative for people with OAS, a diagnosis is often made when these traditional tests are coupled with a history of OAS symptoms. Some allergists will also perform what’s referred to as a “fresh prick by prick” test. This entails pricking the raw fruit or vegetable with a skin prick testing device and then pricking the skin of the patient. This test is generally more accurate because the proteins in raw fruits and vegetables are often not as processed as the allergy extracts commonly used in traditional skin prick tests. Fascinating, right?
Do you have an OAS story? If so, we’d love to hear it! Drop it in the comments below!
— Meg and the Amulet Team
Amulet advisors Dr. Jordan Scott and Dr. John Lee have reviewed this piece for accuracy.
Dr. Scott is board certified in allergy/immunology and operates several private allergy clinics throughout the Boston area at Northeast Allergy, Asthma and Immunology. He is on the philanthropic board at Boston Children's Hospital and is the past President of the Massachusetts Allergy & Asthma Society. Dr. Scott is the current Treasurer for the New England Allergy Society and the Massachusetts Allergy & Asthma Society.
Dr. Lee is the Clinical Director of the Food Allergy Program and the Allergy Director of the Eosinophilic Gastrointestinal Disease (EGID) Program at Boston Children's Hospital. He's also an Instructor of Pediatrics at Harvard Medical School. Dr. Lee is widely recognized for his work in food allergy and for his commitment to patient health.
This is an updated version of an article originally posted in June 2017.