Small and Kim Allergy, Asthma & Clinical Immunology 2011, 7(Suppl 1):S3 http://www.aacijournal.com/content/7/S1/S3 R E V I E W Allergic rhinitis Peter Small1*, Harold Kim2,3 Abstract ALLERGY, ASTHMA & CLINICAL IMMUNOLOGY Open Access Allergic rhinitis is a common disorder that is strongly linked to asthma and conjunctivitis. It is usually a long- standing condition that often goes undetected in the primary-care setting. The classic symptoms of the disorder are nasal congestion, nasal itch, rhinorrhea and sneezing. A thorough history, physical examination and allergen skin testing are important for establishing the diagnosis of allergic rhinitis. Second-generation oral antihistamines and intranasal corticosteroids are the mainstay of treatment. Allergen immunotherapy is an effective immune- modulating treatment that should be recommended if pharmacologic therapy for allergic rhinitis is not effective or is not tolerated. This article provides an overview of the pathophysiology, diagnosis, and appropriate management of this disorder. Introduction Rhinitis is broadly defined as inflammation of the nasal mucosa. It is a common disorder that affects up to 40% of the population [1]. Allergic rhinitis is the most com- mon type of chronic rhinitis, affecting 10 to 20% of the population, and evidence suggests that the prevalence of the disorder is increasing. Severe allergic rhinitis has been associated with significant impairments in quality of life, sleep and work performance [2]. In the past, allergic rhinitis was considered to be a dis- order localized to the nose and nasal passages, but cur- rent evidence indicates that it may represent a component of systemic airway disease involving the entire respiratory tract. There are a number of physiolo- gical, functional and immunological relationships between the upper (nose, nasal cavity, paranasal sinuses, pharynx and larynx) and lower (trachea, bronchial tubes, bronchioles and lungs) respiratory tracts. For example, both tracts contain a ciliated epithelium consisting of goblet cells that secrete mucous, which serves to filter the incoming air and protect structures within the air- ways. Furthermore, the submucosa of both the upper and lower airways includes a collection of blood vessels, mucous glands, supporting cells, nerves and inflamma- tory cells. Evidence has shown that allergen provocation of the upper airways not only leads to a local inflamma- tory response, but also to inflammatory processes in the lower airways, and this is supported by the fact that 1Sir Mortimer B. Davis Jewish General Hospital, Division of Allergy & Clinical Immunology, Montreal Quebec, Canada Full list of author information is available at the end of the article rhinitis and asthma frequently coexist. Therefore, aller- gic rhinitis and asthma appear to represent a combined airway inflammatory disease, and this needs to be con- sidered to ensure the optimal assessment and manage- ment of patients with allergic rhinitis [1,3]. Comprehensive and widely-accepted guidelines for the diagnosis and treatment of allergic rhinitis were pub- lished in 2007 [1]. This article provides an overview of the recommendations provided in these guidelines as well as a review of current literature related to the pathophysiology, diagnosis, and appropriate manage- ment of allergic rhinitis. Pathophysiology In allergic rhinitis, numerous inflammatory cells, includ- ing mast cells, CD4-positive T cells, B cells, macro- phages, and eosinophils, infiltrate the nasal lining upon exposure to an inciting allergen (most commonly air- borne dust mite fecal particles, cockroach residues, ani- mal dander, moulds, and pollens). The T cells infiltrating the nasal mucosa are predominantly T helper (Th)2 in nature and release cytokines (e.g., interleukin [IL]-3, IL-4, IL-5, and IL-13) that promote immunoglo- bulin E (IgE) production by plasma cells. IgE produc- tion, in turn, triggers the release of mediators, such as histamine and leukotrienes, that are responsible for arteriolar dilation, increased vascular permeability, itch- ing, rhinorrhea (runny nose), mucous secretion, and smooth muscle contraction [1,2]. The mediators and cytokines released during the early phase of an immune response to an inciting allergen, trigger a further cellular © 2011 Small and Kim; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.