Alder (Alnus) is one of the first trees to release pollen into the air — often in the middle of winter when all other trees are still bare. For allergy sufferers this means the pollen season actually starts much earlier than many expect, and symptoms in sensitive individuals can appear as early as January or February.
What plant are we talking about
The most common in our region are black alder (Alnus glutinosa), which grows near water — streams, rivers, and wet soils — and gray alder (Alnus incana). Alder belongs to the birch family (Betulaceae), the same as birch, hazel, and hornbeam, and it shares related allergens with them.
Alder is wind-pollinated and releases large quantities of pollen from catkins that develop before leaves appear, so the wind carries pollen over large distances.
Season
- January through March, depending on weather and mild winters
- in warm winters flowering can start as early as late December
- alder regularly opens the season of woody allergens, before or alongside hazel, and before birch
How strong an allergen is it
Alder is classified among the moderate to strong allergens. By itself it triggers clear symptoms in sensitive individuals, but its main importance lies in the fact that it extends and moves the season forward for all those sensitive to birch and related trees.
Cross-reactions
The main alder allergen (Aln g 1) is very similar to the main birch allergen (Bet v 1), so cross-reactivity with birch is almost a rule — those who react to birch usually also react to alder. There is also relationship with other members of the Fagales order (hazel, hornbeam, oak).
Due to relationship with birch, oral allergy syndrome is possible — itching or swelling of the mouth after apples, hazelnuts, or stone fruits in a portion of sensitive individuals.
Symptoms
- watery discharge and nasal congestion
- sneezing
- itching and redness of the eyes
- itching of the palate and throat
- in sensitive individuals — worsening asthma
Diagnosis
- skin prick tests for alder and birch simultaneously
- specific IgE blood tests (Aln g 1, along with Bet v 1) when skin tests are unreliable
- keeping a symptom diary — very early winter symptoms point precisely to alder and hazel
What helps
- Second-generation antihistamines — start in time, at the announcement of season
- Nasal corticosteroid spray for pronounced or prolonged symptoms
- Eye drops for allergic conjunctivitis
- Ventilation at times of day with lower concentrations, avoid drying laundry outside
- Specific immunotherapy is usually planned according to birch as the leading Fagales allergen; whether to include alder is decided by the allergist based on test results
Note
This is not medical advice. If you suspect you have an allergy to alder pollen or any other pollen, consult your family doctor or allergist. Due to strong relationship with birch, accurate diagnosis helps select the right therapy and prepare for early season.