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Ragweed pollen

Ragweed (Ambrosia artemisiifolia) is airborne here from august to october, peaking late August and September. Allergenic potency: high. Cross-reacts with melon, watermelon, cucumber, courgette 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

Ragweed is a North American annual that has naturalised across central and south-eastern Europe — Hungary, the Balkans, Ukraine, northern Italy and southern France — where it is a first-rank allergen. In the Nordic and Baltic countries it is not established as a widespread population: it turns up in scattered casual occurrences, often traced to imported bird seed and to soil disturbance, and monitoring programmes have worked to keep it that way.

When it is in the air

What reaches the north is mostly long-distance transport. Ragweed pollen released in central and eastern Europe in late August and September travels with the right weather systems, and monitoring in the Baltic and Nordic countries picks up episodes rather than a local season. Those episodes are short, weather-driven and can be intense.

What it feels like

Intense rhinitis and eye symptoms confined to short spells in late summer, appearing without an obvious local cause. Where symptoms follow travel to central or south-eastern Europe in September, ragweed is the leading candidate.

What it cross-reacts with

Ragweed and mugwort are relatives and cross-react strongly, which is why a person sensitised in one region often reacts in the other. The best-known food link is the melon family: melon, watermelon, cucumber and courgette, plus banana and chamomile. Reactions are usually oral, but the melon group has a reputation for being more than that in some people.

Related pollens: mugwort and other daisy-family plants.

Foods reported to cross-react:

MelonWatermelonCucumberCourgetteBananaChamomile tea

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: Amb a 1 (the major allergen), Amb a 8 (profilin), Amb a 11. These are the official WHO/IUIS names, and they are what a component-resolved blood test reports.

What actually helps

Ragweed is one of the five types in the CAMS European forecast, which is genuinely useful precisely because the exposure here is episodic and imported: the forecast can show a plume arriving. Anyone who has recognised this pattern should also expect worse symptoms when travelling south in late summer.

What gets misread

Two errors are common. The first is assuming ragweed is a normal part of the northern calendar; it is not established here and the exposure is mostly transported. The second is assuming it is therefore irrelevant — the transported episodes are real, they are measured, and they can be strong.

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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