Should patients with oral allergy syndrome (OAS) avoid all foods that trigger allergic reactions?

From the Guidelines

No, patients with oral allergy syndrome (OAS) do not necessarily need to avoid all foods that trigger mild allergic reactions. For many individuals with OAS, simply cooking or processing the triggering fruits and vegetables often destroys the allergens responsible for symptoms, making them safe to consume 1. If symptoms are mild and limited to temporary itching or tingling in the mouth and lips, patients can try peeling fruits, as the proteins causing reactions are often concentrated in the skin. Canned or cooked versions of trigger foods are typically well-tolerated. However, if a patient experiences more severe symptoms like throat tightness, difficulty breathing, or systemic reactions, they should strictly avoid those specific trigger foods and carry an epinephrine auto-injector (such as EpiPen or Auvi-Q) as prescribed by their healthcare provider, as recommended by guidelines for the diagnosis and management of food allergy in the United States 1.

Key Considerations

• OAS occurs because proteins in certain raw fruits and vegetables are similar in structure to pollen allergens, causing cross-reactivity in allergic individuals, but these proteins are often heat-labile, explaining why cooked forms may be tolerated.
• Patients with a history of severe reactions to foods should be educated on avoidance and management of accidental ingestion, and should carry epinephrine auto-injectors as prescribed by their healthcare provider 1.
• The allergist-immunologist can evaluate the risks and explain possible approaches to prevent allergy in food allergy–prone children, and can perform diagnostic tests to determine the cause of reactions in individuals with symptoms associated with food exposure 1.

Management of OAS

• Milder forms of allergic reactions, such as flushing, urticaria, isolated mild angioedema, or symptoms of OAS, can be treated with H1 and H2 antihistamine medications 1.
• Patients should be educated on how to read and interpret labels on foods, and how to inquire about ingredients in restaurant meals to avoid accidental ingestion of trigger foods 1.

From the Research

Oral Allergy Syndrome (OAS) and Food Avoidance

• Patients with OAS may not need to avoid all foods, but rather identify and avoid specific trigger foods that cause allergic reactions 2, 3.
• Trigger foods are often fresh fruits, vegetables, and nuts that are structurally similar to pollen, and can be cooked to reduce the risk of an allergic reaction 3.
• Avoiding trigger foods is a key part of therapy for OAS, in addition to antihistamine medications and other treatments 2.

Diagnosis and Management of OAS

• Diagnosis of OAS involves a clinical history, skin tests, and oral provocation tests 2, 4.
• Dental clinicians should take a thorough history and be alerted to the possibility of OAS when symptoms such as pruritus of oral mucosal tissues appear immediately after eating certain foods 3.
• Patients with OAS may be at risk of anaphylaxis, particularly if they consume concentrated or unusual forms of plant food allergens such as smoothies, juices, or nutritional supplements 5.

Prevalence and Risk Factors of OAS

• The prevalence of OAS varies by geographic region and the predominant pollen type, affecting between 30% and 60% of food allergies 4.
• OAS is more common in adults and adolescents than in young children, and is often associated with seasonal allergic rhinitis and other atopic conditions 6.
• Patients with OAS may have some risk factors in addition to pollen allergy, and those with more severe atopy are more likely to develop OAS 6.