You still hurt when you eat. Your tongue swells, your throat tightens and the tell-tale churn and burn of the same old acid reflux welcomes you to yet another painful meal. “But all the tests were negative,” you might think. Or you might plead, “But I’m confident I’ve cut gluten from my life, and this meal is 100% gluten-free!”

If healthy foods make your lips, tongue or throat itch and swell, you may be suffering from Oral Allergy Syndrome (OAS).

I suspect oral allergy syndrome remains largely undiagnosed, and some evidence suggests it could be one of the most common food-related allergies in adults. It is different from many allergies in that it is less common in children; it is far more common in late teens and adults.

• What Is Oral Allergy Syndrome?
• How Is This Different From Other Food Allergies?
• OAS Symptoms
• Related Conditions
• Oral Allergy Syndrome Food List and Chart
• Exercise-Induced Food Allergies
• Diagnosis
• OAS Treatment and Prevention
• Final Thoughts
• Take The Quiz

What Is Oral Allergy Syndrome?

OAS is a food allergy where people with a pollen allergy also experience allergic reactions to foods containing proteins structurally similar to the proteins in their pollen allergen. For this reason it is sometimes called Pollen-Food Allergy.

Cross-reactivity occurs when you experience an allergic reaction or intolerance to a protein similar to a well-defined allergy or intolerance. For example, some people with celiac disease experience cross-reactivity to a protein in oats (although that is not an allergic cross-reactivity — it is an autoimmune cross-reactivity).

In OAS, the cross-reactivity occurs when proteins in specific nuts, fruits and vegetables are structurally similar proteins to specific pollens (see below for a food list and chart).

If you experience hay fever or a known allergy to a pollen, such as the pollen from grass, trees or ragweed, you have the potential to experience OAS. Like the allergies to these pollens, OAS is most common during the spring and early summer allergy seasons, but it can occur any time of the year.

OAS is a true allergy: it is a type 1 hypersensitivity where an immediate or near-immediate reaction occurs. Your immune system produces IgE antibodies against the allergen (in this case pollen or the protein similar to the allergic pollen protein), which results in a histamine response.

In most cases this reaction occurs with raw or fresh foods. Cooking, canning, or freezing may denature the problem proteins. This creates confusion as someone might enjoy something like canned peaches without difficulty but then experience an uncomfortable reaction to a nice, fresh peach.

How Is This Different From Other Food Allergies?

The main difference is that an OAS reaction is a cross-reaction to food with similarities to another protein, where that other protein is the primary allergen.

For example, a peanut allergy is not part of OAS: it is a serious allergy directly to peanuts.

However, because a protein in almonds and hazelnuts is similar to a protein in alder trees, someone with a tree allergy to alder may experience OAS when they eat almonds or hazelnuts.

So you wouldn’t necessarily say this person is allergic to almonds or hazelnuts; you would say they are allergic to alder and cross-reactive to almonds or hazelnuts.

I know this is a little confusing, but I hope this helps.

Oral Allergy Syndrome Symptoms

These are the most common oral allergy syndrome symptoms:

• Acid reflux
• Esophageal swelling and burning
• Hay fever, including itchy, watery eyes, runny nose, congestion and sneezing.
• Hives (urticaria) or Eczema
• Itching or Tingling in the mouth and throat
• Swelling of the lips, face, tongue or throat (including the uvula)
• Wheezing, throat tightening or trouble breathing

In people with stronger allergies, the proteins may survive stomach acids and create gastrointestinal distress, including gas, cramping and diarrhea.

While most cases involve relatively minor symptoms, please note that anaphylactic reactions are possible. If you have a history of severe allergic reactions or anaphylactic shock and you suspect you may suffer from OAS, I urge you to seek formal diagnosis and treatment from an allergy specialist.

Anaphylaxis can come fast and be fatal, so proper diagnosis and treatment is critical.

Related Conditions

Some people with allergies to grasses, especially barley and rye grasses, may experience cross reactivity to wheat. Thus, some forms of OAS may appear to be a wheat allergy. Please see my lesson on wheat allergy symptoms for more.

Urticaria (hives) and asthma sometimes occur when OAS patients prepare food. This may happen when you touch or inhale the cross-reactive proteins.

Some people with a form of chronic rhinitis, a condition where the mucus membranes of the nose are chronically inflamed, may have experienced OAS for years without diagnosis.

The most common related condition is hay fever. If you are an adult who suffers from hay fever each spring and summer, you are at greater risk for experiencing an oral allergy syndrome.

If you believe you’ve reacted to eating certain raw or fresh foods and you suspect OAS, I urge you to discuss the matter with an allergy specialist so you can accurately diagnose and treat it.

Oral Allergy Syndrome Food List and Chart

In what first appears contradictory, ripe fresh foods often cause more severe reactions than fresh-picked foods, and cooked or canned foods cause less severe reactions than fresh foods.

So a fresh-picked apple right off the tree will cause less of a reaction than the apple that’s been sitting in your fruit bowl for a couple of days.

In some cases, such as with apples and carrots, peeling the fruit or vegetable appears to minimize or eliminate the reaction.

Here are the most common pollens in Oral Allergy Syndrome, along with their most common cross-reactive foods:

Alder

• almonds
• apples
• celery
• cherries
• hazelnuts
• parsley
• peaches
• pears

Birch

• almonds
• apples
• apricots
• carrots
• celery
• cherries
• coriander (cilantro)
• fennel
• hazelnuts
• kiwi
• nectarines
• parsley
• parsnips
• peaches
• pears
• peppers
• plums
• potatoes
• prunes
• walnuts

Grass

• celery
• figs
• melons (watermelon, cantaloupe, honeydew)
• oranges
• peaches
• tomatoes
• wheat

Latex

• avocado
• bananas
• chestnut
• kiwi
• papaya

Mugwort

• apple
• carrots
• celery
• coriander (cilantro)
• fennel
• kiwi
• parsley
• peanuts
• peppers
• sunflower seeds

Ragweed

• bananas
• chamomile (including the tea made from chamomile)
• cucumber
• dandelions
• melons (watermelon, cantaloupe, honeydew)
• sunflower seeds
• zucchini

Please note:

I’ve tried to make this list comprehensive, but it’s unlikely anyone can put a 100% accurate and complete list together. It is possible to react to foods that aren’t on this list. However, I believe this list will cover the most common cases.

Remember that food restrictions can compromise nutrition unless you really know what you’re doing and you are deliberate in your nutritional choices. For this reason, I encourage you to see an allergy specialist if you suspect OAS. Self-diagnosing and unnecessarily removing healthy foods from your diet may only reduce your long-term health.

Exercise-Induced Food Allergies

OAS can be associated with exercise-induced allergies. In some cases, it can be related to exercise-induced anaphylaxis (EIA). While the condition isn’t entirely understood yet, understanding how cross-reactivity to something you eat triggers a reaction may help you prevent EIA.

If you’ve experienced an exercise-induced allergic reaction and you don’t know why, you might discuss OAS with your allergy specialist.

Diagnosis

Diagnosing oral allergy syndrome can be difficult for several reasons. Cooking, canning, freezing and pasteurizing the allergen can reduce or eliminate reactions, making it difficult to identify or even suspect certain foods.

In addition, other food reactions, including the symptoms of gluten intolerance or lactose intolerance may cause patients to inaccurately self-diagnose.

Sometimes other conditions may hide behind OAS. For example, oral allergy syndrome may mask a food intolerance resulting from the inability to metabolize certain proteins or salicylates in food.

To obtain an accurate diagnosis, you need to work with an allergy specialist familiar with all these possibilities.

Your doctor may use the following to diagnose OAS:

• Elimination diet (often followed by a food challenge)
• History of symptoms (arguably the most important one here)
• Oral food challenge (done in the office)
• Radioallergosorbent test (RAST), or a Fluorescence Enzyme-Labeled Assay – These are food allergy blood tests used to identify antibodies to specific food proteins.
• Skin prick test

However, doctors often like you to keep a detailed food journal and symptom history so they can narrow down the allergy tests you need and avoid random testing.

Many may find this process challenging in a world of diet trends and self diagnosis, but it’s important to let the data speak for itself rather than imposing preconceived notions on to that data.

I’ve come across cases where people who diagnosed themselves with gluten intolerance later learned they actually suffered from oral allergy syndrome unrelated to wheat.

While I don’t mean to dissuade you from diagnosing a wheat allergy or a gluten intolerance, remember that the goal is to find out what’s wrong and get better.

The goal is not to fulfill a confirmation bias, something that happens more often than people like to admit, especially during an era when the anti-wheat bandwagon barrels through Internet blogs like a party bus without brakes.

OAS Treatment and Prevention

If you want to learn how to prevent oral allergy syndrome, the most important step is to obtain an accurate diagnosis. Food journals are tedious and unpopular, but maintaining one can save you from a lifetime of frustration resulting from inaccurate diagnoses or missed diagnoses.

For someone with a broad range of food allergies (unfortunately, it happens), allergen immunotherapy through allergy shots may be considered. Such therapy doesn’t exist for celiac disease or non-celiac gluten sensitivity, but it can help people with OAS or a wheat allergy.

Long term, improving your immune system may help minimize symptoms of OAS. To improve your immune system try the following: exercise daily, improve your amount and quality of sleep, drink plenty of water (soda pop and alcoholic beverages don’t count), reduce sugars, take a probiotic supplement and take a gluten-free multivitamin.

For immediate treatment, I recommend a rigorous cold water rinse and an oral antihistamine. Benadryl (diphenhydramine) appears to be particularly effective. While the brand name Benadryl is expensive, the same medication is sold as a generic sleep aid in some markets. You may find generic sleep aids where the only ingredient is diphenhydramine a cheaper alternative to Benadryl.

Other oral antihistamines like Claritin (Loratadine) may work for you as well. Keep in mind that Claritin works better taken well in advance of an allergic reaction, while Benadryl works better if you take it right as a reaction begins.

People with severe allergic reactions may need to keep a couple of epinephrine autoinjectors (EpiPens) on hand at all times. These are often necessary to curb potentially deadly reactions like anaphylaxis.

Final Thoughts On Oral Allergy Syndrome

I suspect many more people suffer from oral allergy syndrome than we currently understand. It may be the trigger of problems blamed on other conditions or allergens. It may sometimes remain within a tolerable threshold, so many people choose not to do much about it.

If your negative reactions to food are often immediate and you’ve tested negative for celiac disease or a wheat allergy, I encourage you to watch your diet closely for reactions to the foods I detailed in the oral allergy syndrome list.

If you discover a new pattern relating to those foods, discuss this pattern with an allergy specialist for accurate diagnosis. I sincerely hope this helps someone out there discover a new opportunity for healing.

Take The Oral Allergy Syndrome Quiz!