Allergies are a very common health problem with 5 to 50% of the world population - that is approx. 400 million to 4 billion people suffering from allergic rhinitis (1). Allergic rhinitis is an inflammation in the nose, triggered by an overreaction of the immune system to allergens in the air (2). If allergic rhinitis occurs only seasonally and against tree or grass pollen, it is called hay fever. The prevalence of allergic rhinitis depends on factors like geographic location, population density and age and is reported to increase over the years, as climate change is associated with increased seasonal pollen exposures (1). As a result, the prevalence of allergies is expected to increase by more than 50% in the next few decades, particularly in colder climates that previously were spared from higher rates of seasonal pollen allergies (1).
