Allergy is defined as an immunological hypersensitivity reaction that may lead to a variety of diseases (e.g. anaphylaxis, urticaria, angioedema, allergic rhinoconjunctivitis, allergic asthma, allergic vasculitis) through distinct pathological mechanisms. Therefore, different approaches may be applied to the diagnosis, treatment, and prevention of allergic diseases.

Allergic diseases affect the lives of more than one billion people worldwide. Following an epidemic-like increase over the past 60 years, the prevalence of allergic diseases is expected to reach 4 billion people by the 2050s.

Allergic rhinitis (AR) is a symptomatic disorder of the nose occurring after exposure to an allergen and caused by IgE-mediated inflammation of the nasal membranes. The main symptoms of AR are nasal itching, sneezing, rhinorrhea, and nasal congestion. Ocular symptoms are also common. Allergic rhino conjunctivitis is associated with itching, redness of the eyes, and tearing. Other symptoms may include an itchy palate, postnasal drip, and cough. In addition, AR is frequently associated with asthma, and uncontrolled moderate-to-severe AR has been shown to affect asthma control.

It is classified as:

• Intermittent or persistent, based on the duration of symptoms

• Mild or Moderate/Severe, based on symptom severity

Compared with other medical conditions, AR may appear not to be serious because it is not associated with significant morbidity and mortality. However, AR adversely affects the quality of life of many patients by reducing sleep quality and cognitive function, while causing irritability and fatigue. Allergic rhinitis is associated with reduced performance at school and work, particularly during the peak pollen season. In Europe, the prevalence of confirmed AR among adults ranges from 17% to 28.5%.

This information is intended for the general information and education of the public and under no circumstances can replace the advice of a physician or other qualified healthcare professional.

Urticaria is a common, heterogeneous disease with a wide variety of underlying causes. It is characterized by the development of wheals lasting 1–24 hours and/or angioedema, which may persist for up to 72 hours. Histamine is the key mediator in urticaria and in most cases of angioedema.

It is classified according to its duration as:

• Acute urticaria (≤ 6 weeks)

• Chronic urticaria (> 6 weeks)

It is estimated that up to 25% of adults will experience at least one episode of acute urticaria at some point in their lives, while the prevalence of chronic urticaria alone is approximately 3%.

This information is intended for the general information and education of the public and under no circumstances can replace the advice of a physician or other qualified healthcare professional.