Allergic rhinitis (AR; commonly known as hat fever) is a secondary condition that results from inflammation of the nasal mucosa, with symptoms including rhinorrhea (runny nose), sneezing, coughing, itching, and general discomfort. In cases of AR, the immune system responds to allergens by releasing histamine and chemical mediators. Downstream effects and comorbidities, however, can be more serious: sinusitis, nasal polyposis, sleep disorders, and a general decreased quality of life are possible complications.
The World Allergy Organization reported in 2013 that more than 40% of patients who have AR suffer from asthma, and more than 80% of patients with asthma have contracted AR. Moreover, 10-30% of adults, and 40% or more children have AR. The condition is most often caused by environmental allergens like pollens, dust mites, molds, and insects. There are several effective and safe treatment options, ranging from simple allergen avoidance, to pharmacotherapies (antihistamines) or immunosuppressive drugs (corticosteroids). Antihistamines work by blocking the effect of released histamine, which is present in high amounts during allergic reactions. While they are effective at controlling many symptoms of AR, they generally have little effect on treating nasal congestion. Corticosteroids act by decreasing inflammatory cells and inhibiting the release of cytokines, thus reducing inflammation of the nasal mucosa, leading to reduction in nasal congestion. Nasal, topical, and oral corticosteroids work similarly in reducing the symptoms of rhinitis, regardless of cause.