Alder Allergy: Symptoms, Treatment and Cross-Reactivity

Alder is one of the first trees to flower — sometimes as early as February, while snow is still on the ground. For anyone with hay fever, that means one thing: the season has started. Alder allergy opens the spring pollen cycle and is often the first wake-up call that sends someone to an allergist for the first time. Here's what causes it, what symptoms look like, which foods trigger cross-reactions, and how to treat it — from antihistamines to immunotherapy.

Why Alder Causes Allergy

Alder belongs to the birch family and produces some of the most aggressive pollen in temperate climates. The main culprit is a protein called Aln g 1, which is structurally similar to key proteins in birch, hazel, and hornbeam pollen. This similarity explains why sensitivity to alder almost always comes with reactions to other related trees.

The allergic immune system works like an overzealous security guard: it identifies the harmless pollen protein as a threat and launches a full inflammatory response. Histamine floods in, blood vessels dilate, and mucous membranes swell — leaving the person sneezing, weeping, and struggling to breathe, even though nothing dangerous is actually present.

Key risk factors:

• Genetics — if both parents have allergies, the child's risk reaches 60–80%.
• Living in regions with abundant alder — especially near rivers and wetlands.
• Pre-existing birch or nut allergy — cross-sensitization works in both directions.

Symptoms of Alder Allergy

Depending on the region, alder flowering runs from late February through April. Symptoms appear with the first warm days and disappear as soon as flowering ends — this seasonal pattern is what distinguishes pollinosis from chronic rhinitis.

Typical symptoms:

• Runny nose — watery, clear discharge with paroxysmal sneezing in runs of 10–15 times.
• Conjunctivitis — red, itchy eyes with tearing and a "sand in the eye" sensation.
• Itching in the nose, palate, and throat — a persistent tickle that can't be scratched away.
• Dry cough — paroxysmal; wheezing may indicate bronchospasm.
• Fatigue and headache — often mistaken for a cold.

A tell-tale sign: symptoms sharply worsen outdoors on dry and windy days — especially in the morning — and ease significantly after rain or indoors with windows closed.

Cross-Reactivity: Which Foods to Avoid

Alder pollen allergy almost always comes with cross-reactions. The Aln g 1 protein is structurally similar to proteins in certain fruits, vegetables, and nuts — the immune system treats them the same way.

Group	Foods
Trees	Birch, hazel, hornbeam, oak
Fruits and berries	Apples, pears, cherries, peaches, apricots, plums
Vegetables	Carrots, celery, potatoes, parsley
Nuts	Hazelnuts, almonds
Other	Kiwi, birch sap

Cross-reactivity usually presents as oral allergy syndrome: itching and tingling in the mouth and throat within minutes of eating raw foods. Heat destroys the allergenic protein — cooked carrots are usually safe, raw ones are not.

Most patients with alder allergy also struggle during the birch season. The triggers and cross-reactive foods largely overlap — see our guide to birch allergy for a detailed comparison.

How to Confirm the Diagnosis: Tests

Symptoms alone can't confirm alder allergy — they look too similar to a cold or other allergic conditions. An allergist will order:

• Skin prick tests — a small amount of alder allergen (code t2) is placed on the skin and pricked. Results in 20 minutes. Performed outside the pollen season and at least 2 weeks after stopping antihistamines.
• Specific IgE blood test for alder — measures antibody levels. Can be done any time of year; antihistamines don't affect the result.
• Molecular diagnostics — identifies exactly which protein is triggering the reaction and predicts the risk of severe systemic responses.
• Complete blood count — an indirect marker: eosinophils are often elevated during allergic conditions. Not diagnostic on its own, but supports the picture.

How to Treat Alder Allergy

Treatment works on three levels — only their combination produces lasting results.

Avoidance: Reduce Pollen Exposure

• Stay indoors on dry, windy days during flowering season, especially between 6 and 11 am when pollen counts peak.
• Keep windows closed; use a HEPA air purifier at home.
• After every outing: shower, rinse your nose with saline, change clothes.
• Wear wraparound sunglasses — they physically block pollen from reaching your eyes.

Medication

• Second-generation antihistamines (cetirizine, fexofenadine, bilastine) — taken daily throughout the season, starting 2 weeks before the expected bloom.
• Intranasal corticosteroids (mometasone, fluticasone) — the most effective way to reduce swelling and congestion. They act locally and are not absorbed into the bloodstream.
• Eye drops (azelastine, olopatadine) — for allergic conjunctivitis.
• Cromones — useful for mild symptoms and preventive treatment.

Immunotherapy — The Only Cause-Based Treatment

Allergen-specific immunotherapy (AIT) doesn't just manage symptoms — it tries to retrain the immune response itself. Patients receive gradually increasing doses of alder allergen (sublingual or by injection), teaching the immune system to tolerate it. The course runs 3–5 years. Most patients see a 50–70% symptom reduction in the first year, and many achieve long-term remission after completing the course.

AIT is started only during remission — in autumn or winter, well outside the pollen season.

When to Seek Urgent Medical Attention

Call emergency services immediately if:

• You experience difficulty breathing, wheezing, or a feeling of suffocation.
• Swelling of the lips, tongue, or throat (angioedema) develops.
• Blood pressure drops suddenly, you feel dizzy or lose consciousness.

Schedule a routine visit to an allergist if:

• Symptoms recur every spring and affect your daily life.
• Antihistamines no longer provide adequate relief.
• You notice reactions to cross-reactive foods listed above.
• You want to start a course of immunotherapy.

Conclusion

Alder allergy is more than spring discomfort. Without treatment it tends to progress: the list of triggers expands, reactions intensify, and the risk of asthma rises. But this is one of the best-managed allergic conditions — and even reversible with immunotherapy. The earlier treatment begins, the better the chances of lasting remission.

Any hay fever symptoms warrant a consultation with an allergist. Self-prescribing medications for pollinosis can be dangerous — treatment is always prescribed by a doctor after proper diagnosis.