eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Allergy

Allergic Rhinitis

Author: Quoc A Nguyen, MD, Associate Clinical Professor, Director, Sinus and Allergy Center, Department of Otolaryngology-Head & Neck Surgery, University of California, Irvine Medical Center
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Updated: Jun 1, 2009

Introduction

Background

Allergic rhinitis is a common health problem for which many patients do not seek appropriate medical care. Although not a life-threatening condition in most cases, it has a substantial impact on public health and the economy.

According to findings in a recent study, the total estimated cost of allergic rhinitis in 1994 was between 1.2 and 1.5 billion dollars.¹ The illness resulted in more than 6 million missed work days, 2 million missed school days, and 28 million reduced-activity days. These figures are certainly higher today because of the higher cost of new medications and the increasing prevalence of the condition.

Pathophysiology

Because the nose is the most common port of entry for allergens, in patients with allergies, signs and symptoms of allergic rhinitis, not surprisingly, are the most common complaints.

Four types of hypersensitivity responses exist, as initially classified by Gell and Coombs and later modified by Shearer and Huston. Individuals with allergic rhinitis are thought to have type I reactions.

After initial exposure to an antigen, antigen-processing cells (macrophages) present the processed peptides to T helper cells. Upon subsequent exposure to the same antigen, these cells are stimulated to differentiate into either more T helper cells or B cells. The B cells may further differentiate into plasma cells and produce immunoglobulin E (IgE) specific to that antigen. Allergen-specific IgE molecules then bind to the surface of mast cells, sensitizing them.

Further exposures result in the bridging of 2 adjacent IgE molecules, leading to the release of preformed mediators from mast cell granules. These mediators (ie, histamine, leukotrienes, kinins) cause early-phase symptoms such as sneezing, rhinorrhea, and congestion. Late-phase reactions begin 2-4 hours later and are caused by newly arrived inflammatory cells. Mediators released by these cells prolong the earlier reactions and lead to chronic inflammation.

Frequency

United States

Approximately 39 million Americans are reported to have allergic rhinitis. From various studies, 17-25% of the population in the United States are estimated to have the condition.

Mortality/Morbidity

• Allergic rhinitis is frequently associated with otitis media, rhinosinusitis, and asthma, either as a precipitating and/or aggravating factor or a symptomatic comorbid condition.
• Allergic rhinitis can significantly decrease the quality of life and impair social and work functions, either directly or indirectly, because of the adverse effects of medications taken to relieve the symptoms.

Sex

Males and females tend to be affected by allergic rhinitis in fairly equal proportions.

Age

• Allergic rhinitis appears mainly to affect individuals younger than 45 years.
• The condition may begin to appear in patients as young as 2 years and usually reaches a peak in those aged 21-30 years.
• It then tends to remain stable or slowly decrease until patients are aged 60 years, when again the prevalence may increase slightly.

Clinical

History

• Allergy history
  • For the clinician who treats patients with allergic rhinitis, nothing is more crucial than the allergy history. It is important not only in identifying an allergy but also in guiding the treatment plan.
  • Although history taking begins at the initial encounter, it should not be completed at a single sitting, and it should be continued during subsequent visits, as needed.
  • Details about the presenting symptoms (eg, onset, fluctuation, severity) should be obtained. In addition, the interviewer should note any recent changes in the patient's life (eg, at home, in the workplace, in leisure activities, in diet).
• Family history
  • Children of individuals with allergies have been shown to have a higher incidence of allergies than that of other children.
  • If both parents have allergies, their child has a 50% chance of having the same problem.
• Past medical history
  • In children, a history of recurrent otitis media, upper respiratory tract infection, asthma, chronic rashes, and formula intolerance are suggestive of allergies.
  • Other pertinent medical problems (eg, asthma, aspirin hypersensitivity) and the use of medications (eg, beta-blockers, tranquilizers) that could interfere with the treatment for allergies should be evaluated.
  • Inquire about the results of previous allergy tests and treatment.

Physical

Patients with allergies frequently have a characteristic physical appearance.

• Face
  • Patients with allergic rhinitis frequently grimace and twitch their face, in general, and nose, in particular, because of itchy mucus membranes.
  • Chronic mouth breathing secondary to nasal congestion can result in the typical adenoid facies.
• Eyes
  • Patients may have injected conjunctiva; increased lacrimation; and long, silky eyelashes.
  • Dennie-Morgan lines (creases in the lower eyelid skin) and allergic shiners (dark discoloration below the lower eyelids) caused by venous stasis may be present.
• Ears
  • Ears are frequently unremarkable.
  • Eczematoid otitis externa and middle ear effusion may be present.
• Nose
  • A transverse nasal crease may be present because of the patient's repeated lifting of the nasal tip to relieve itching and open the nasal airway.
  • The turbinates are frequently hypertrophic and covered with a boggy pale or bluish mucosa.
  • Nasal secretions can range from clear and profuse to stringy and mucoid.
  • The presence of polyps does not necessarily indicate that the affected individual has allergic rhinitis.
• Mouth
  • A high arched palate, narrow premaxilla, and receding chin may be present secondary to long-term mouth breathing.
  • The posterior oropharynx may be granular because of irritation from persistent postnasal discharge.

Causes

For practical purposes, allergens can be divided into seasonal and perennial groups.

• Seasonal allergens are primarily pollens. In general, trees bloom in the spring; grasses, in the summer; and weeds, in the fall. Information about regional allergens can be obtained from manufacturers of allergy-treatment supplies, local botanic gardens, universities, and newspapers.
• Perennial allergens of importance are molds, house dust, and animal danders. Although these allergens are present throughout the year, they tend to be more problematic during the winter, when people spend most of their time indoors.
  • Molds can be either indoor or outdoor allergens. Perennial symptoms that worsen in cool, humid weather suggest mold sensitivity. The major manufacturers of allergy-treatment supplies have lists of predominant molds in each region. Significant reservoirs of molds include indoor plants, refrigerator drip pans, areas under sinks, and compost piles.
  • House dust is a mixture of approximately 28 allergenic components. The actual major allergen appears to be a collection of degrading lysine residues.
    • For practical reasons, the component of house dust that most closely resembles the overall extract consists of dust mites (although they are much less immunologically potent than the overall extract).
    • The 2 major dust mites in the United States are Dermatophagoides pteronyssinus and Dermatophagoides farina. These mites thrive in warm (65-80°F), humid (>70% relative humidity) environments. They are abundant in mattresses, pillows, upholstered furniture, and carpets.
    • Another significant ingredient of house dust is decomposing cockroach body parts, which can be a problem even in buildings that appear to be free of the live insect.
  • A person does not need to own a pet to be exposed to dander, such as cat dander, which can cling to clothing and be brought into classrooms and homes. Dog dander, however, tends to be primarily a problem for its owner. The dander of other pets such as rabbits and hamsters is also highly allergenic.

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