Is Oral Allergy Syndrome Dangerous?

Sep 12, 2023

Is Oral Allergy Syndrome Dangerous?

4 minute read

When spring comes around, you may begin to experience the watery eyes, scratchy throat, and sneezy nose associated with hay fever. These allergy symptoms occur when a foreign substance – such as pollen or grass – comes into contact with your immune system. If you are allergic, your body will fight these “intruders”, so it signals different responses to your body to try to keep them out.

If you’ve ever bitten into an apple and gotten a similar reaction, you may have oral allergy syndrome.

What is Oral Allergy Syndrome?

Oral allergy syndrome (OAS) is an allergic reaction of the mouth, lips, tongue, and throat as a response to consuming certain fruits, vegetables, nuts, and spices.

It’s not exactly the same as a food allergy because you’re not technically allergic to the food itself, your immune system confuses certain proteins in some fruits, vegetables, nuts, and spices with pollen proteins. This triggers what's called a [cross reaction]( Often, symptoms of OAS are much milder than the symptoms of common food allergies.

Individuals with hay fever or seasonal allergies to tree, grass or weed pollens are more likely to develop oral allergy syndrome than those who don’t experience seasonal allergies.

OAS tends to appear in teenagers and young adults. You could be enjoying a delicious pear – a fruit you’ve eaten your entire life without issue – and feel an itchy or numbing sensation on your lips and tongue. This may be the start of OAS cross-reactivity.

What Causes OAS?

As the immune system mistakens proteins found in certain fruits and vegetables for pollen allergens, it defends itself by communicating a series of responses to flush out any “pollen” invasions. You can find the most common pollen types with their associated foods here:

  • Birch Pollen: Apple Almond Carrot Celery Cherry Hazelnut Kiwi Peach Pear Plum

  • Alder Tree Pollen: Celery Cherry Apple Almond Hazelnut Peach Pear Parsley

  • Ragweed Pollen: Banana Cucumber Melons Sunflower seeds Zucchini White potato

  • Mugwort Weed Pollen: Aniseed Bell pepper Black pepper Broccoli Cabbage Caraway Cauliflower Chard Coriander Fennel Garlic Onion Parsley

  • Timothy and Orchard Grass Pollen: Orange Peach Tomato Watermelon White Potato

What this suggests is that if your allergies are caused by ragweed pollen, you may not be able to start your morning with a banana anymore. If alder tree pollen is what’s causing you to spend all of the month of April sneezing, eating peaches and pears may cause some uncomfortable symptoms, too.

These specific food “allergies” may vary from person to person, but these are the widely established cross-reactions associated with each of these major allergens.

Health experts have also found that it is possible for those with OAS to consume the delicious foods they’re missing out on — but under specific circumstances.

The proteins causing this cross-reactivity are mostly found in the skin. With certain fruits and vegetables in which the skin is typically eaten, peeling the skin before consumption may enable you to enjoy them – sans all the unpleasant symptoms.

Additionally, cooking these fruits and vegetables will often distort the proteins. The immune system does not register the malformed proteins as allergens, so it doesn’t send in its defenses. As a result, you may be able to enjoy some of your favorite fruits and veggies with no problem.

Symptoms of Oral Allergy Syndrome

As the name suggests, the symptoms of OAS tend to be much more prominent in the mouth.

The most common symptoms include numbness, tingling, and scratchiness in the mouth (tongue, throat, and lips).

While oral allergy syndrome commonly has very mild symptoms, rarely some individuals may experience more severe symptoms and even anaphylaxis (which requires immediate medical attention as it is a life-threatening situation).

Exercise caution with your food choices if you've experienced any symptoms similar to the ones mentioned when consuming raw fruits, vegetables, nuts, or specific spices. You should see a specialist to get evaluated so that you have the proper treatments and know how to stay safe.

How is Oral Allergy Syndrome Diagnosed?

Oral allergy syndrome can be diagnosed with a combination of your history of symptoms and a skin prick test or a blood test to confirm an allergy to pollens.

With a prick test, the skin is scratched to allow a tiny amount of the allergen solution to enter just below the surface. If the person is allergic, the small area surrounding the prick will have an immediate reaction.

Is OAS Seasonal?

Though hay fever does not typically occur all year ‘round, oral allergy syndrome usually does. However, there are certain times of the year in which symptoms can peak.

Tree and grass pollination season (between April and June) can worsen symptoms or cause reactions from foods that don’t typically contribute to symptoms. September and October may bring on symptoms again as weeds undergo pollination.

Do Symptoms of Oral Allergy Syndrome Go Away on Their Own?

After you’ve had a mild reaction, symptoms of OAS will subside on their own. This can take a few minutes but shouldn’t normally take more than an hour.

Severe reactions (much rarer in OAS) may lead to anaphylaxis, which is life-threatening. Call 911 immediately, as anaphylaxis is a medical emergency.

How Can You Treat Oral Allergy Syndrome?

Oral allergy syndrome is typically a lifelong condition, but there are ways to help you manage reactions. These include:

Avoiding triggers: If you’ve had a mild reaction to a specific food even once or twice, your immune system is most likely experiencing cross-reactivity. Avoid the fruits, vegetables, nuts, and spices that cause you any uncomfortable or worrisome symptoms. Buying canned fruits and vegetables: Canned fruits and vegetables may limit the reactions, as they are often better tolerated than the raw form. Removing the skin: OAS proteins are usually found in the skin. Peeling the skin off fruits and vegetables may reduce symptoms. Cooking fruits and vegetables: Cooking or heating destroys the proteins the body is confusing with allergens, so cooked fruits and vegetables rarely cause symptoms of OAS. OTCs: Over-the-counter antihistamines such as cetirizine can relieve allergy symptoms of OAS. The common brands you can find at your local drug store are Zyrtec, Aller-tec, and All Day Allergy. Immunotherapy: This process involves gradually exposing the immune system to small amounts of allergens. An allergist can help you learn more about immunotherapy and determine if it’s right for you.

Seeking Help from a Medical Provider

If you suspect you have developed oral allergy syndrome, be sure to contact a licensed medical professional. Cleared by LifeMD can connect you with a doctor or nurse practitioner to help you determine the best route of treatment for your OAS. Don’t let OAS stop you from exploring the foods you love. Make an appointment to get personalized allergy treatment – all from the comfort of your home.


Dr. Payel Gupta

Medically reviewed by Dr. Payel Gupta



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