Patients
Allergies are a frequent health problem, which according to the World Health Organisation (WHO) occupy fourth place in terms of worldwide prevalence. In recent decades, allergies have been on the rise, reaching significant levels in Western countries. It is estimated that 20% of the world's population suffers from some type of allergy.
According to the WHO, allergies represent "an important public health problem in terms of quality of life, days away from work or the classroom, cost of medicines and hospitalisations, among others".