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Oral allergy syndrome (OAS) is a type of food allergy-induced by raw fruits and uncooked vegetables, as well as some herbs, spices, nuts, and seeds. It is also called pollen-food allergy syndrome or pollen fruit syndrome.

OAS is found in people with seasonal allergies to environmental pollens. If you have OAS, your immune system is unable to differentiate between certain pollens and the proteins found in specific foods. The primary symptoms are itching, tingling, and/or swelling of the mouth, lips, and/or throat. In most cases, OAS reactions are mild and resolve quickly.

Symptoms tend to begin soon after an allergen-containing food is put into your mouth, and typically do not last long after the food is swallowed. You may develop itching, redness, or slight swelling of the hands if you peel or otherwise handle particular fruits or vegetables (apples, white potatoes).

An estimated 10 percent of individuals with OAS may also experience nausea or stomach upset after eating triggering foods. Less than 5 percent of those with OAS suffer from more serious allergic reactions, such as throat and/or chest tightness, difficulty breathing, vomiting, diarrhea, or loss of consciousness.

OAS is diagnosed in both children and adults, but the disorder mostly affects adults and teenagers. In the last five to 10 years, OAS has become recognized as the most common type of food allergy in adults.

All people with OAS have a pollen allergy, but it is possible for you to be unaware of the pollen allergy. Your primary care provider can assess the presence of pollen. Skin and blood allergy tests may confirm any suspected allergies. An allergist can clarify your diagnosis and help you to create an appropriate food avoidance and management plan.

Reducing OAS Symptoms

Not all of the foods linked with one of the pollens will necessarily initiate an allergic response. Some varieties of products may cause a stronger reaction than others. For example, Granny Smith apples generate more OAS symptoms than Fuji apples.

Allergic reactions are usually the most severe if a food is eaten during (and possibly for a few months after) the related pollen season. Factors that worsen OAS symptoms include:

• Consuming a very large amount of a symptom-inducing food
• Engaging in vigorous exercise immediately after eating
• Drinking alcohol
• Sleep deprivation
• Affliction with a minor illness
• Using narcotics or other medicines for pain or fever (ibuprofen, aspirin)

These elements can influence your body’s digestion and nutrient absorption. So, you should avoid them in combination with any foods that cause OAS symptoms.

Heat breaks down the proteins associated with the syndrome. The best way to minimize an allergic response is to cook any offending foods. Microwaving fruit for at least 10 seconds can sometimes destroy enough of the allergen so that the fruit will no longer instigate your symptoms. However, this does not work for every person or for all foods.

Canned, processed, pasteurized, and frozen foods are typically safe and unlikely to provoke an allergic reaction. On the other hand, many people still experience symptoms after eating dried or dehydrated foods. If you wish to eat food that triggers your allergies without cooking them, try peeling it. Most of the proteins you will want to avoid are located in the skin.

Treatment of OAS

There is not a specific medication to treat OAS. However,  the condition can usually be managed like a pollen allergy. Antihistamines, immunotherapy, and epinephrine (for serious reactions) are three recommended courses of action.

Eliminating foods that cause OAS symptoms, at least in the raw, dehydrated, and dried forms, is frequently considered to be sufficient treatment. It is not necessary to avoid foods that do not cause symptoms.

All reactions to nuts should be interpreted with caution and discussed with your health care provider. OAS has been linked to both raw and roasted nuts, but nuts can also cause life-threatening allergic reactions unrelated to pollen.

For more information about oral allergy syndrome or how to treat your allergies, please contact your primary care provider.

Examples of OAS Allergens

REFERENCE: Italicized entries are preliminary and require further research

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