Oral allergy syndrome



What is Oral allergy syndrome?

Oral allergy syndrome is an allergic reaction that specifically affects the mouth, lips, tongue, and throat. It is related to allergic rhinitis, otherwise known as hay fever.

In oral allergy syndrome, the body cross-reacts to certain proteins in specific foods. These proteins are similar to the proteins found in the pollens that are associated with hay fever and seasonal allergies.

As these foods are typically available throughout the year, oral allergy syndrome is not seasonal.

How common is Oral allergy syndrome?

Oral allergy syndrome typically does not appear in young children; the onset is more common in older children, teens, and young adults who have been eating the fruits or vegetables in question for years without any problems. Please discuss with your doctor for further information.


What are the symptoms of Oral allergy syndrome?

Symptoms of oral allergy syndrome only occur after eating specific foods. The symptoms vary significantly, and can peak at different stages of life.

Mild symptoms include:

  • Itching of the throat, mouth, lips, or tongue
  • Swelling, particularly of the lips and tongue

More severe symptoms include:

  • Swelling of the throat
  • Nausea and vomiting

Additional symptoms can include hives and asthma. Typically, hives occur when the food is being peeled, chopped, or grated. Asthma occurs when the food is being blended or otherwise vaporized, such as during stir-frying.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

In 9 percent of people with oral allergy syndrome, symptoms can become more severe and require medical intervention. If you have a reaction to a pollen-based food that extends beyond the area of your mouth, you should seek medical attention.

In some very rare cases, OAS can trigger anaphylaxis.

In other cases, people confuse their serious nut or legume allergies with oral allergy syndrome. Make sure you speak to your doctor about the intensity and severity of your symptoms. You might need to be referred to an allergist to be certain that your symptoms are caused by oral allergy syndrome.

If you or your loved one has any signs symptoms listed above or you have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes Oral allergy syndrome?

Proteins are found in all organic matter. The immune system identifies specific proteins in order to target bacteria, viruses, and other unwanted germs. However, it sometimes identifies everyday proteins, such as pollens, as harmful as well.

After being eaten or breathed in, these proteins are available in large numbers and the immune system identifies them as abnormal. The body reacts with a significant immune response, which leads to swelling, various other allergy symptoms, and discomfort.

Experts estimate that more than 60 percent of all food allergies are actually cross-reactions to pollen allergies. The most common cause of allergic rhinitis in the United States is birch pollen. However, multiple trees, grasses, and weeds can cause it as well.

Typically, oral allergy syndrome can be traced back to an allergy to the following:


  • Birch
  • Alder
  • Japanese cedar
  • Plane


  • Timothy
  • Orchard grass


  • Wormwood
  • Ragweed
  • Mugwort
  • Parietaria species

Common foods that cause oral allergy syndrome


  • Prunus genus: Cherries, nectarines, peaches, plums, apricots
  • Apples and pears
  • Mangoes
  • Bananas
  • Figs
  • Avocados
  • Strawberries
  • Raspberries
  • Kiwis
  • Watermelons
  • Melons
  • Oranges


  • Apiaceae family: Celery, carrots, parsley, parsnips, cilantro, cumin, dill, chervil, and fennel
  • Nightshades: Tomatoes, potatoes, and peppers
  • Cucurbitaceae family: Pumpkins, butternut squashes, zucchini, cucumbers
  • Lettuce
  • Corn
  • Artichokes
  • Peas


  • Hazelnuts and walnuts
  • Peanuts
  • Chickpeas
  • Wheat
  • Soy
  • Almonds
  • Lentils
  • Sunflower seeds
  • Honey

Risk factors

What increases my risk for Oral allergy syndrome?

People who have allergies to birch pollen, grass pollen, and ragweed pollen are most likely to have oral allergy syndrome, according to the American College of Allergy, Asthma, and Immunology.

Young children are not usually affected by OAS. Often, young adults will have symptoms of OAS for the first time after having eaten trigger foods for years without a problem.

The pollination season of April, May, and June tend to be the peak months for oral allergy syndrome. Sometimes September and October will bring on symptoms again as leaves fall from the trees and seeds are heavy in the air.

Please consult with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is Oral allergy syndrome diagnosed?

Diagnosing oral allergy syndrome often involves several steps. Typically, these include clinical and laboratory methods.


Clinical methods are the most common. Diagnosis requires confirmation of allergic rhinitis along with itching and tingling that develops after eating fresh fruit or vegetables. In many cases, an accurate patient history shows a link between eating a specific type of food and the start of tingling or swelling.

In other cases, the doctor may propose an elimination diet. The person avoids specific food groups that may cause oral allergy syndrome for a set amount of time and records whether it makes a difference.


[a doctor does an allergy test on a patient’s arm]

A dermatologist can diagnose allergies by using a prick test and measuring the level of reaction.

Laboratory tests typically involve skin testing via a prick test, a scratch test, or a blood test. For skin testing, a dermatologist marks out a grid on the back or the forearm and applies extracts of pollens, fruits, or vegetables. Any marks that develop on the skin are measured after 15 minutes to determine the level of reaction.

If prick tests with the pollen are positive but the food itself fails to provoke a reaction, the person may be asked to eat a certain amount of the suspected food. A reaction immediately after eating this food will confirm the presence of oral allergy syndrome.

In some cases, blood tests might be used to diagnose the condition. First, the doctor performs a test to work out the total level of antibodies in the blood. Another test then checks for specific antibodies. Blood tests are often used when skin tests are not available or practical.

How is Oral allergy syndrome treated?

The best treatment for oral allergy syndrome is straightforward: Avoid your trigger foods.

Over-the-counter treatments

Over-the-counter histamine blockers, or antihistamines, used for hay fever may work for oral allergy syndrome symptoms, according to a paper published in Allergy. Diphenhydramine (Benadryl) and fexofenadine (Allegra) can be used to relieve the itching, watery eyes, and scratchy throat that come during high-pollen days for people with allergies. They can sometimes suppress OAS reactions as well.


People that were treated with immunotherapy for OAS have had mixed reactions. In one clinical study, subjects could tolerate small amounts of the birch pollen triggers after immunotherapy, but they couldn’t overcome OAS symptoms completely.

Because the symptoms of OAS are not dangerous, ask your general health practitioner if you can experiment once in a while and see what you react to.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage Oral allergy syndrome?

The following lifestyles and home remedies might help you cope with Oral allergy syndrome:

  • Cook or heat your food. Preparing food with heat changes the chemical composition, and many times eliminates the allergen.
  • Buy canned versions of a vegetable or fruit.
  • Peel the skin off vegetables or fruit. The offending protein is often found in the skin of the produce.Wearing gloves when peeling fruits can reduce the symptoms of hives. Not stir-frying vegetables can also reduce the risk of asthma.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: February 8, 2018 | Last Modified: February 11, 2018

You might also like