Frequently asked questions about hay fever

Hay fever (allergic rhinitis) is a hypersensitivity reaction of the immune system to pollen. With repeated exposure, the body produces antibodies (IgE). As soon as pollen reaches the mucous membranes of the nose, eyes or throat, histamine and other substances are released that cause the typical symptoms.

Common symptoms include: frequent sneezing, watery or itchy eyes, blocked or runny nose, throat irritation, fatigue and concentration problems. In severe cases, asthmatic symptoms such as wheezing or shortness of breath can also occur.

With hay fever, symptoms begin quickly after contact with pollen and the eyes are more often affected (itching, tearing). A cold is accompanied by thicker mucus, sometimes fever and general fatigue, and lasts 7–10 days. Hay fever persists as long as the pollen season lasts and disappears on its own outside the season.

Yes. Hay fever can develop at any age. The immune system can develop an allergy after repeated exposure to pollen — sometimes only after years. Climate change is causing longer and more intense pollen seasons, making more people susceptible.

There is a genetic predisposition for allergies. If one parent has hay fever, the chance that a child will also develop it is about 30–40%. If both parents are allergic, this increases to 60–80%. However, genes are not the only factor: environment and lifestyle also play a role.

The hay fever season starts as early as January with alder and hazel pollen and continues until September with weed pollen. Key periods: alder/hazel (Jan–Mar), birch (Apr–May), grass (May–Aug), mugwort and amaranth (Jul–Sep). Peak moments vary by year and region.

Grass pollen is responsible for hay fever in most people (May–August). Birch pollen (April–May) and mugwort pollen (July–September) are also common causes. In early spring, alder and hazel often cause symptoms already.

Yes, rain washes pollen from the air — concentrations are significantly lower right after a shower. As soon as it clears up and the temperature rises, pollen is quickly released and concentrations rise rapidly. Right after a thunderstorm, short-lived high peaks can occur (thunderstorm asthma).

Pollen concentrations are typically highest between 7:00 and 10:00 AM and in the early afternoon (11:00–14:00). In cities, concentrations can also rise in the evening as pollen that rose during the day settles back down. After sunset, concentrations in rural areas are generally lower.

No. Regional differences are significant. Birch pollen is higher in forested areas (Veluwe, Brabantse Wal). Grass pollen is higher in agricultural areas (Groningen, Flevoland). Coastal areas generally have slightly lower concentrations due to sea breeze. Cities can have higher concentrations than the surrounding countryside due to the urban heat effect.

Higher temperatures cause plants to bloom earlier and for longer. Higher CO₂ concentrations stimulate pollen production, causing plants to produce more and sometimes more aggressive pollen. Scientists expect the hay fever season in the Netherlands to extend by another 2–4 weeks in the coming decades.

Non-sedating antihistamines (cetirizine, loratadine, fexofenadine) reduce sneezing, nasal discharge and eye itching. Corticosteroid nasal sprays (fluticasone, mometasone, budesonide) are most effective for severe nasal symptoms — start 2 weeks before the season. Eye drops (cromoglicate or antihistamine) help with eye symptoms. Consult a doctor for personal advice.

Immunotherapy (allergen immunotherapy) is the only treatment that addresses the underlying allergy. Through injections or tablets/drops under the tongue, the immune system is gradually accustomed to the allergen. After 3–5 years, symptoms are greatly reduced or gone in 70–80% of patients. Ask your GP about the options.

A thin layer of petroleum jelly or a special pollen barrier (such as HayMax) on the inside of the nostrils can block some pollen before it reaches the mucous membranes. It is not a replacement for medication, but can be a useful addition on dry, windy days with high pollen concentrations.

Yes, an air purifier with a HEPA filter (class H13 or H14) can filter pollen and fine particles from indoor air and significantly reduce indoor pollen concentrations. Combine this with keeping windows closed during peak hours (10:00–16:00) for the best results.

Preferably exercise in the early morning (before 7:00) or after a rain shower, when pollen concentrations are lower. The gym or swimming pool are safe alternatives on peak days. Wear a sports mask or pollen filter for outdoor sports. Take a shower and wash your hair immediately after exercising to remove pollen.

Yes, through cross-reactivity. People sensitive to birch pollen sometimes react to apples, pears, peaches, cherries, plums, carrots and hazelnuts. Grass pollen sensitivity can cause reactions to tomatoes, peanuts or wheat. The reaction is usually mild (oral itching), but for severe symptoms, allergological advice is recommended.

Cross-reactivity occurs when proteins in food or other plants resemble pollen proteins that cause an allergy. The immune system then mistakenly reacts to those other substances. Well-known combinations: birch pollen + apple-family fruits/carrots, grass pollen + peanuts/wheat, mugwort + celery/herbs.

Through an allergy test at your GP or allergist. The most common methods are the skin prick test and a blood test (specific IgE). Your GP can refer you if symptoms are severe or do not respond to regular medication.

Hay fever is most common between the ages of 5 and 45. In young children (under 3 years), it is rare; the allergy typically develops after several years of exposure. Teenagers and young adults are most often affected. In some people, symptoms decrease after the age of 50.