Allergic rhinitis is one of the most common allergic disease, and its prevalence is steadily increasing, especially in industrialized countries. Allergic rhinitis is a disease of the nasal mucosa caused by hypersensitivity to various allergens, among which the most frequent are:
• house dust mites;
• ollen of various plants;
• hair and organic material from cats and other animals.
Allergic rhinitis is often associated with asthma, since the upper and lower airways display the same immune response to allergens. Two forms of allergic rhinitis can be distinguished based on time of onset, i.e. seasonal (typically associated with pollination) and perennial (allergens not related to seasonality). Allergic rhinitis usually manifests with acute attacks of nasal discharge of mucus (runny nose), sneezing, feeling of nasal obstruction, and nasal itching. These symptoms are reversible either spontaneously or in response to therapy. Rhinitis is often associated with conjunctivitis, which is always of allergic origin (allergic rhinoconjunctivitis); in such case, there are symptoms affecting the eyes, including: tearing, redness and burning of the eyes, intolerance to light (photophobia), foreign body sensation. Other frequent comorbidities are bacterial and fungal rhinosinusitis, nasal polyps, otitis (i.e. ear infections), viral respiratory infections, food allergies, and sleep disorders.
The treatment of choice for allergic rhinitis is the elimination of the allergen inducing the symptoms. Therefore, in case of allergy to dust mites it is recommended to cover mattresses and pillows with covers that are impermeable to dust mites, as well as keeping indoor relative humidity below 50%. Patients with allergies to pets should avoid keeping pets at home; in case of pollen allergy, it is recommended to limit time spent outdoors during the pollination season. Further measures are the use of vacuum cleaner with HEPA filters, and the reduction of any potentially “irritating” stimulus, e.g. cigarette smoking (including passive smoking) or inhalation of sprays, aerosols, perfumes, and environmental dust.
Systemic antihistamines are particularly effective in reducing nasal itching, sneezing, and nasal discharge nose, while antileukotrienes exert a predominantly anti-inflammatory effect. Chromones, which are administered as nasal sprays, should be used before exposure to the allergen, as they act by inhibiting the activation of mast cells. Topical decongestants and topical (intranasal) corticosteroids, that are also administered as nasal sprays, represent a non-specific symptomatic treatment. An adjunct to symptomatic drug treatment is the use of nasal irrigation with topical nasal sprays containing isotonic sodium chloride solution.