If you’ve ever bitten into an apple during hayfever season and felt a strange tingle across your lips, tongue, or throat, you’re not imagining it—and you’re far from alone. Pollen food allergy syndrome (PFAS), sometimes called oral allergy syndrome (OAS), is one of the most common food allergy in adults. Estimates vary by region, but a 2019 review in the Annals of Allergy, Asthma & Immunology reported 13-58% of adults with pollen allergies are affected; among those allergic to birch pollen, rates may reach 50-90%.
Despite its prevalence, PFAS remains poorly understood by many who experience it, often mistaken for a primary food allergy.
What’s Actually Happening
Your immune system recognizes birch, grass, or ragweed pollen as a threat, producing IgE antibodies targeted at pollen proteins—this is standard for hayfever. Certain raw fruits, vegetables, and nuts contain similar-shaped proteins (e.g., Mal d 1 in apples mimicking Bet v 1 in birch pollen), triggering cross-reactivity. IgE in oral mucous membranes binds these, causing localized itching, tingling, or mild swelling in the mouth/throat—symptoms start within minutes and resolve quickly. Serious reactions like hives, breathing issues, or anaphylaxis are rare (~1.7%).
Why Cooking Fixes It
PFAS proteins are heat-labile; cooking, baking, canning, or pasteurizing denatures them, preventing recognition—e.g., raw apples trigger symptoms, but apple pie does not. Peeling often helps, as proteins concentrate in skins. Exceptions: nuts (e.g., hazelnuts) and celery have heat-stable proteins, risking reactions even cooked—consult an allergist.
Which Pollen, Which Food?
Cross-reactivity varies by pollen (not all listed foods affect everyone). Data from clinical studies, AAAAI, ACAAI, and EAACI:
Birch pollen (UK peak: March-May)
- Fruits: apple, pear, cherry, peach, nectarine, apricot, plum, kiwi, strawberry, fig, mango
- Vegetables: carrot, celery, parsnip, potato, pepper, tomato
- Nuts/legumes: hazelnut, almond, walnut, peanut, soy
- Herbs/spices: parsley, coriander, fennel, dill, cumin, aniseed
Grass pollen (UK peak: mid-May-July)
- Fruits: melon, orange, kiwi, watermelon, tomato
- Vegetables: potato, Swiss chard
- Other: peanut, wheat
Mugwort pollen (UK peak: July-September; “celery-mugwort-spice syndrome”)
- Fruits: apple, melon, watermelon, peach, mango
- Vegetables: carrot, celery, parsnip, pepper
- Herbs/spices: aniseed, caraway, coriander, fennel, parsley, sunflower seeds, chamomile
Ragweed pollen (UK less common; peak: August-September)
- Fruits: banana, watermelon, cantaloupe, honeydew
- Vegetables: cucumber, courgette (zucchini), white potato
- Other: sunflower seeds, echinacea, chamomile tea
Why It Comes and Goes
Symptoms peak during relevant pollen seasons due to higher IgE levels. Ripeness, fruit variety (e.g., Granny Smith vs. Braeburn apples), and life stage matter—PFAS rarely starts in young children, emerging later after pollen sensitization.
What to Do About It
Avoid only symptomatic raw foods; cook/process them to denature proteins. Peel if possible; symptoms may vanish off-season. See an allergist for systemic symptoms (hives, breathing issues), nuts/celery reactions, or diet impact—pollen immunotherapy may reduce PFAS as a bonus. Track symptoms seasonally.
Seasonal Cheat Sheet (UK)
- Spring (March-May): Birch → stone fruits, apples, carrots, hazelnuts
- Summer (June-July): Grass → melons, kiwi, tomatoes
- Late summer (August-September): Mugwort/ragweed → celery, spices, bananas, melons
Sources
- Carlson G, Coop C. Pollen food allergy syndrome (PFAS): A review… Ann Allergy Asthma Immunol. 2019;123(4):359-365. doi:10.1016/j.anai.2019.07.022
- Buhler S et al. Oral allergy syndrome. CMAJ. 2010;182(11):1210-1211.
- ACAAI. Pollen Food Allergy Syndrome. acaai.org.
- Stanford Health Care. OAS info sheet. stanfordhealthcare.org
- EAACI. Pollen-Food-Latex Chart. eaallergy.com [web:23]
- Skypala IJ et al. Questionnaire for OAS diagnosis… Clin Exp Allergy. 2013
- Bucher X et al. Birch immunotherapy effect on OAS… Allergy. 2004;59:1271-1276
This is informational, not medical advice. Seek professional care for severe reactions.