Seasonal allergies

Seasonal allergies (Pollinosis): Causes and mechanisms

Seasonal allergy, also known as pollinosis or hay fever, is an allergic reaction to plant pollen carried by the wind. For millions of people, spring, summer and autumn become periods of battling runny nose, sneezing and itchy eyes. This is a classic example of an IgE-mediated allergic reaction, where the immune system overreacts to completely harmless particles in the air.

Why does a reaction to pollen occur?

Pollen consists of microscopic grains necessary for plant reproduction. In allergy‑prone individuals, the immune system recognizes pollen proteins as foreign and dangerous. When inhaled, pollen settles on the mucous membranes of the nose and eyes, triggering a cascade of reactions with the production of IgG antibodies and subsequent release of histamine. Histamine causes the classic symptoms of pollinosis: swelling of the nasal mucosa (congestion), excessive mucus secretion (runny nose), irritation of nerve endings (sneezing, itching).

Allergy calendar: Spring, summer, autumn

Seasonal allergy symptoms are closely linked to the flowering periods of specific plants:

• Spring (March‑May): Tree flowering period. Main “culprits” are birch, alder, hazel, oak.
• Summer (June‑July): Flowering of meadow and cereal grasses such as timothy, rye, pearl millet.
• Late summer – autumn (August‑October): Weed flowering, the main one being ragweed. Ragweed pollen is one of the most aggressive allergens.

Seasonal allergy can significantly worsen quality of life and is also one of the main triggers of exacerbations of bronchial asthma. This condition belongs to the broader group of environmental allergies.