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Hazel pollen

Hazel (Corylus avellana) is airborne here from february to april, peaking March, and late February in a mild year. Allergenic potency: moderate. Cross-reacts with apple, pear, cherry, plum and others.

This is reference information, not a diagnosis and not a treatment plan. A pollen calendar cannot tell you what you are allergic to, and no page can clear a food as safe for you — only the label on the packet in your hand and the clinician who knows your history can do that. Anything beyond mild, short-lived symptoms in the mouth or nose — swelling that affects breathing or swallowing, hives away from the mouth, wheeze, vomiting or faintness — is an emergency question, not a reading question.

● peak weeks · ○ usually airborne. Typical mainland window from the national aerobiology monitoring programmes of the region · checked 2026-09-06

Where it grows here

Hazel grows as a multi-stemmed shrub along forest edges, in hedgerows and in gardens right across the Baltic states and the southern half of the Nordic region, and it is planted as an ornamental well beyond its wild range. It flowers long before it leafs out: the soft yellow catkins hanging from bare branches in late winter are the male flowers, and one mature bush sheds pollen for weeks.

When it is in the air

Hazel opens the pollen year, usually a few days ahead of alder. In Denmark and Skåne the first grains are routinely caught in January when the winter is mild; in Estonia, Latvia and southern Finland the season normally runs from February into April with the heaviest days in March. Hazel is driven by accumulated warmth rather than day length, which makes it the most weather-dependent season of the year: one warm week starts it, and a cold spell can shut it down again for a fortnight before it restarts.

What it feels like

Late-winter hay fever is routinely mistaken for a cold that will not clear. The pattern that gives it away is the weather: itchy eyes, sneezing runs and a clear, watery nose on bright still days in February and March, and almost nothing during rain or a hard frost. A cold does not switch off when it rains.

What it cross-reacts with

Hazel sits in the same order as birch, and its main pollen allergen Cor a 1 is a PR-10 protein closely related to birch Bet v 1. People who react to hazel pollen therefore react to alder, birch and oak as well, and carry the birch food list. The hazelnut is the confusing part: the nut contains both a birch-type PR-10 that causes an itchy mouth and the heat-stable storage proteins Cor a 9 and Cor a 14, which cause the serious, non-pollen kind of hazelnut allergy. The two are different problems that happen to share a name.

Related pollens: alder, birch, oak, hornbeam and beech — the whole Fagales order.

Foods reported to cross-react:

ApplePearCherryPlumPeachHazelnutCarrotCelery

A cross-reaction is not the same as a food allergy that started with food, and the difference decides how serious it is. Read how oral allergy syndrome works before drawing conclusions from this list, and note that several of these foods also appear on the fourteen declarable EU allergens for entirely separate reasons.

Named allergen molecules: Cor a 1 (PR-10, a Bet v 1 homologue). These are the official WHO/IUIS names, and they are what a component-resolved blood test reports.

What actually helps

Because the season is short and early, hazel is the one most people treat reactively rather than in advance. If February and March are reliably bad years for you, that is the argument for starting a preventive antihistamine or steroid nasal spray before the catkins open rather than after — a conversation for a pharmacist or GP, since the timing depends on which medicine you use.

What gets misread

Hazel gets blamed for symptoms that belong to house dust mite. Mite allergy is at its worst in the same late-winter months, indoors, in heated bedrooms — and unlike hazel it is no better when it rains and no worse when the sun comes out. If your February symptoms are worst on waking and best outdoors, the calendar is not the explanation.

Sources: Regulation (EU) No 1169/2011, Annex II · Commission Implementing Regulation (EU) No 828/2014 (gluten claims) · WHO/IUIS Allergen Nomenclature · season windows from the national aerobiology monitoring programmes of Estonia, Finland, Sweden, Denmark and Norway · cross-reaction patterns paraphrased from the allergy literature and EAACI material · checked 2026-09-06

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