Paeds · allergy-and-immunology
Oral allergy syndrome and pollen-food syndrome
Also known as Oral allergy syndrome · Pollen-food allergy syndrome · Pollen-food syndrome · PFAS · Birch-fruit syndrome · Cross-reactive food allergy
A fellowship approach to pollen-food allergy syndrome (oral allergy syndrome) in children: recognise the local oral reaction to raw fruit or vegetable in a pollen-sensitised child, explain the cross-reactive labile-versus-stable protein mechanism, use history plus fresh-food skin-prick and component-resolved diagnostics, counsel on keeping cooked forms while avoiding the raw trigger, and know when an adrenaline autoinjector is needed for the lipid-transfer-protein systemic-risk phenotype, across ANZ, UK, US and Canada.
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Target exams
Red flags
- Any urticaria beyond the mouth, wheeze, abdominal pain or collapse after a raw plant food is systemic — treat as anaphylaxis, not 'just oral allergy syndrome'
- Reactions to the cooked or processed food, or to small amounts, suggest a primary IgE food allergy or a heat-stable lipid transfer protein phenotype, not classic PFAS
- Sensitisation to lipid transfer protein (Pru p 3), especially with peach, carries anaphylaxis risk and needs an adrenaline autoinjector and action plan
- Cofactors — exercise, NSAIDs, intercurrent infection, alcohol — can convert a previously local reaction into a systemic one
- A commercial skin-prick extract that is negative does not exclude PFAS; use the fresh-food prick-prick test when the history is convincing
- A positive skin-prick or IgE with no reaction history is sensitisation, not allergy — do not over-restrict the diet on testing alone
Life stages
Care settings
Clinical exam formats
Board mappings
- General and Community Paediatrics
- Allergy and Immunology
- Current 2026 PREP curriculum — Learning Objective area: allergy, immunology and ambulatory paediatrics
- Renewed curriculum for first-year trainees from 2027 — Learning goal 5: Clinical assessment – essential general paediatrics
- Renewed curriculum for first-year trainees from 2027 — Learning goal 6: Clinical management – essential general paediatrics
- Renewed curriculum for first-year trainees from 2027 — Learning goal 12: Communication with patients, families, and health professionals
- Clinical Applications
- Short Cases
- Long Cases
- 4. Professional skills and knowledge: Patient management
- 7. Patient safety, including safe prescribing
- General Paediatrics: allergy and ambulatory presentations in children
- Foundation of Practice (FOP)
- Applied Knowledge in Practice (AKP)
- History
- Communication
- Clinical
- General Pediatrics Content Outline — Domain 1: Preventive Pediatrics/Well-Child Care
- General Pediatrics Content Outline — Domain 8: Allergy and Immunology
- General Pediatrics Content Outline — Domain 24: Patient Safety, Quality Improvement, and Research Methods
- Patient Care 5: Patient Management
- Medical Knowledge 1: Clinical Reasoning
- Systems-Based Practice 1: Patient Safety and Quality Improvement
- Interpersonal and Communication Skills 1: Patient- and Family-Centered Communication
- Medical Expert
- Communicator
- Health Advocate
- Pediatrics: Foundations EPA — Providing ambulatory allergy assessment and counselling
Overview & Definition
A nine-year-old with spring hayfever bites into a raw apple and within a minute her lips tingle, her palate itches and her throat feels tight. She eats apple pie every week without trouble. That constellation — oral symptoms to the raw food only, in a pollen-sensitised child — is pollen-food allergy syndrome. [1] [2]
Pollen-food allergy syndrome (PFAS) is an IgE-mediated contact reaction, usually confined to the oropharynx, that follows raw plant-food exposure in a person sensitised to pollen. Oral allergy syndrome (OAS) is the older name, classically reserved for the local oral form; PFAS is now the preferred umbrella term because it acknowledges that some of these reactions go beyond the mouth. [2] [6]
The clinical hallmark is raw but not cooked. The cross-reactive proteins are fragile, so cooking, baking or canning denatures them and the food is tolerated. Holding that idea makes the mechanism, the diagnosis and the dietary advice fall into place. [1] [7]
The trap, and the fellowship discriminator, is the child whose reaction does not respect this rule. Symptoms beyond the mouth, or reactions to the cooked food, point away from classic PFAS and towards a heat-stable lipid transfer protein phenotype or a primary food allergy. [10] [12]
References13ShowHide
- [1]Mastrorilli C Pollen-Food Allergy Syndrome: A not so Rare Disease in Childhood. Medicina (Kaunas), 2019.PMID 31561411
- [2]Poncet P Update on pollen-food allergy syndrome. Expert Rev Clin Immunol, 2020.PMID 32691654
- [3]Sicherer SH Food Allergy from Infancy Through Adulthood. J Allergy Clin Immunol Pract, 2020.PMID 32499034
- [4]Dramburg S EAACI Molecular Allergology User's Guide 2.0. Pediatr Allergy Immunol, 2023.PMID 37186333
- [5]Matricardi PM EAACI Molecular Allergology User's Guide. Pediatr Allergy Immunol, 2016.PMID 27288833
- [6]Saunders S Oral allergy syndrome. Curr Opin Otolaryngol Head Neck Surg, 2015.PMID 25887974
- [7]Fernández-Rivas M Allergies to fruits and vegetables. Pediatr Allergy Immunol, 2008.PMID 19097271
- [8]Giovannini M Diagnosis and Management of Pollen Food Allergy Syndrome to Nuts. J Allergy Clin Immunol Pract, 2024.PMID 38280450
- [9]Kato Y Comprehensive review of pollen-food allergy syndrome: Pathogenesis, epidemiology, and treatment approaches. Allergol Int, 2025.PMID 39278756
- [10]Asero R Why lipid transfer protein allergy is not a pollen-food syndrome: novel data and literature review. Eur Ann Allergy Clin Immunol, 2022.PMID 34092069
- [11]Wolters P Lipid transfer protein allergy: characterization and comparison to birch-related food allergy. J Dtsch Dermatol Ges, 2022.PMID 36184811
- [12]Sicherer SH Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management. J Allergy Clin Immunol, 2018.PMID 29157945
- [13]Simons FE World Allergy Organization Anaphylaxis Guidelines: 2013 update of the evidence base. Int Arch Allergy Immunol, 2013.PMID 24008815