What Are The Dangers of Oral Allergy Syndrome?

Can oral allergy syndrome be dangerous?

While oral allergy syndrome (OAS) is rarely dangerous, it is important to know when to seek emergency medical attention. Severe symptoms of OAS can include difficulty breathing, nausea, and a sudden drop in blood pressure. If you experience a severe allergic reaction when eating certain fruits, vegetables, nuts, or seeds, call 911 immediately.

Get started
Wyndly Allergy

Beat your allergies forever.

Get Started With Wyndly

If you experience an itchy and uncomfortable feeling in your mouth after eating fruits, nuts, or seeds, you could be experiencing oral allergy syndrome (OAS). OAS is a lesser-known reaction that is linked to pollen allergies.

Keep reading to learn about the causes and indicators of OAS.

Why Should You Be Cautious if You Have OAS?

Some of the proteins in certain foods are similar to those in certain types of pollen. If you have OAS and consume those foods, it can produce an immune response with several symptoms similar to if you were exposed to the pollen you are allergic to.

There is a range in the symptoms you can experience, from mild allergy symptoms to more severe allergic reactions. The more serious symptoms, which we'll outline below, can affect your respiratory and circulatory systems, producing a more severe allergic reaction.

Reactions and Symptoms

If you're affected by OAS, you can typically expect to see symptoms within a few minutes of eating an associated food. These symptoms are commonly worse during pollen season when exposed to the pollen that triggers your allergies.

Two of the most common symptoms of OAS include:

  • A tingling sensation and itching that affects your mouth, throat, and possibly lips.
  • Mild swelling and hives within the same areas.

Usually, you can expect these symptoms to subside a few minutes after you stop eating the problematic food. That said, some people can experience worse symptoms of OAS.

Sometimes, OAS can affect your hands, causing redness, itching, and swelling. This will generally happen after handling the raw fruits or vegetables associated with OAS, such as apples or pineapples. Around 1 in 10 people with OAS can experience mild nausea. In rare cases, people with OAS may experience a more severe reaction that can affect the whole body.

If you experience a more severe allergic reaction from eating certain foods, your symptoms could include:

If you experience a severe allergy reaction, you must seek immediate emergency medical attention. Fortunately, most people do not develop the most severe reactions, and symptoms are usually short-lived. Let's take a closer look at a few OAS symptoms. 

Itchy Throat

An itchy throat is a common complaint among sufferers of OAS. While the feeling can be bothersome, it will typically subside soon after spitting out or swallowing the fruit or vegetable that triggered it. If your symptoms persist long after the trigger food has been removed, you should seek medical advice.

Itchy Tongue

You can develop an itchy tongue or even lips alongside the above symptom. Again, these symptoms should subside within several minutes after the triggering food has been swallowed or spat out.

Trouble Swallowing

In rarer cases, OAS can cause your throat to swell, making it difficult to swallow. This reaction can also make breathing more difficult, which is a medical emergency. While symptoms don't usually persist for long, you should seek immediate medical attention in this scenario.


Anaphylaxis is one of the most severe allergic reactions that can affect the body. This potentially life-threatening reaction can develop very quickly in response to your body's immune system overreacting to an allergen. Remember that while a response can be almost immediate, it can also take several hours. Watch out for the following symptoms:

  • Severe swelling in the eyes, lips, feet, and hands
  • Itching skin and hives, small bumps that can occur all over the body
  • Feeling dizzy and light-headed
  • A sudden drop in blood pressure
  • Swelling of the mouth, tongue, and throat
  • Wheezing when drawing a breath or exhaling
  • Stomach pain, nausea, and vomiting
  • Eventually, a loss of consciousness

Somebody suffering from anaphylaxis requires an immediate shot of epinephrine (adrenaline) to combat the body's immune response and restore normal function. Without this urgent treatment, anaphylaxis can be fatal. If you or someone you know is experiencing anaphylaxis, call 911 immediately.

If you know that you're susceptible to this severe allergic reaction, then you need to take immediate steps to avoid your trigger foods in the future.

Types of Foods You Can Be Allergic To

You may react to one or more fruits, vegetables, or seeds and nuts. Here's a list of the most common triggers of OAS:


  • Apples
  • Apricots
  • Banana
  • Cantaloupe
  • Cherries
  • Honeydew
  • Kiwi
  • Orange
  • Peaches
  • Pears
  • Plum
  • Tomato
  • Watermelon


  • Bell Pepper
  • Broccoli
  • Cabbage
  • Cauliflower
  • Carrot
  • Celery
  • Chard
  • Coriander
  • Cucumber
  • Garlic
  • Onion
  • Parsley
  • White Potato
  • Zucchini

Nuts and Seeds

  • Almonds
  • Black Pepper
  • Caraway
  • Fennel
  • Hazelnuts
  • Peanut
  • Sunflower Seeds
  • Soybean

OAS is what's known as a cross-reactivity reaction. Your immune system becomes confused by the similarity between proteins in the trigger food and proteins in pollen belonging to certain trees, grasses, or weeds.

As we mentioned earlier, OAS is linked to having a pollen allergy. The foods outlined above are typically associated with birch tree pollen, alder tree pollen, ragweed pollen, mugwort pollen, or timothy and orchard grass pollen.

Reducing and Managing Symptoms of OAS

The simplest way to avoid an onset of OAS is to avoid the foods that cause it. That said, if you don't want to give up certain foods, there are some steps you can take that may help:

  • Cook or heat trigger foods: Heating food causes the proteins responsible for your reaction to denature (break down and change). This can reduce or even eliminate your immune response.
  • Buy canned produce: Canned fruits or vegetables are often less likely to cause a reaction.
  • Peel produce: In many cases, the food's skin triggers a reaction. By peeling your fruits or vegetables, you might avoid an immune response.

How Sublingual Immunotherapy Can Help

One of the simplest ways to avoid the frustration of OAS symptoms is to stop eating the associated foods. Much like with any allergy, if you cut out the source of your symptoms, then you should be able to live without them. That said, this could mean cutting a substantial portion of foods that you enjoy out of your diet.

Another option is a treatment known as sublingual immunotherapy or SLIT. SLIT could be suitable for you if you want long-term relief from your allergy symptoms or if your allergy symptoms don’t respond to over-the-counter treatments.

Like allergy shots, SLIT exposes your body to trace amounts of the allergens that you’re allergic to, helping your immune system build immunity to your allergies over time. SLIT, however, is a much more comfortable and convenient method for treating OAS than allergy shots. Unlike allergy shots, SLIT does not require painful injections and can be safely administered from the comfort of your home.

With SLIT, studies have shown that you could enjoy decades of relief.

Take Our Allergy Assessment

If you want long-term relief from your allergy symptoms, look no further than Wyndly.  At Wyndly, our allergy doctors can create a personalized treatment plan for your allergies to help you live free from your allergies.

Take our quick online allergy assessment to take the first step on your road to an allergy-free life!

Is Wyndly right for you?

Answer just a few questions and we'll help you find out.

Get Started Today