Allergic Rhinitis

Andrew G. Ayars, MD, and Mathew C. Altman, MD, MPhil

Introduction/Etiology

•Allergic rhinitis manifests with symptoms such as congestion, rhinorrhea, sneezing, itching, and conjunctivitis.

•It is caused by an immunoglobulin E (IgE)–mediated hypersensitivity to aeroallergens, including pollens, dust mites, cockroaches, pets, molds, and fungi.

•Allergic rhinitis is one of the most common chronic illnesses in developed countries.

•It results in marked morbidity that includes decreased quality of life, missed school or work days, and substantial treatment-related costs.

•Treatment strategies include medications, environmental controls, and immunotherapy (subcutaneous and sublingual).

Pathophysiology

•Allergic rhinitis is driven by an IgE antibody–mediated allergic hypersensitivity to aeroallergens.

•IgE signals delivered through the high-affinity type I Fcε receptor on inflammatory cells such as mast cells, eosinophils, and basophils cause the rapid release of inflammatory mediators, such as histamine and leukotrienes.

Clinical Features

•Rhinitis is characterized by >1 of the following nasal symptoms:

—Congestion, rhinorrhea, postnasal drip, sneezing, and itching

—Allergic conjunctivitis symptoms, such as itchy, watery eyes

•Allergic rhinitis symptoms can be variable, depending on

—Seasonal exposure due to pollens from trees, grasses, molds, fungi, and weeds

—Perennial symptoms, which can be triggered by allergens such as dust mites, molds, fungi, cockroaches, and pets

•Allergic rhinitis most commonly develops prior to the age of 20, but it can manifest at any age.

•Other forms of rhinitis symptoms can include

—Infectious rhinitis and/or sinusitis

—Nonallergic rhinitis

—Medication-induced rhinitis

—Nonallergic rhinitis with eosinophilia

▪This is a form of nonallergic rhinitis with associated nasal eosinophilia, most often documented by means of nasal smear.

▪Causes of medication-induced rhinitis can include antihypertensives, nonsteroidal anti-inflammatory drugs, and overuse of α-adrenergic decongestants.

•These other forms often manifest without a seasonal component or without a worsening of symptoms related to environmental exposures.

—Worsening of symptoms around pets

—Seasonal symptoms that correlate with a known regional pollen season

• Testing for allergic sensitizations may be performed with either of the following methods:

— Skin prick testing

▪Bioassay to evaluate the presence of allergen-specific IgE

▪Involves scratching the skin with individual concentrated aeroallergens

▪Results available within 20 minutes

—Serum IgE testing

▪Another option for assessing specific IgE to aeroallergens

▪Sometimes less sensitive than skin testing for aeroallergens

Management

• H₁-antihistamines

—An inexpensive, safe, and generally effective therapy for allergic rhinitis

—Can be delivered as oral or topical nasal agents

—First-generation antihistamines

▪Work well but are often limited by the side effect profile

▪Sedation is a common limiting side effect

—Second-generation antihistamines

▪Well tolerated with similar effectiveness when compared with the first-generation H₁-antihistamines

▪Do not have the systemic effect profile associated with firstgeneration H₁-antihistamines

• Corticosteroids

—Topical (intranasal) corticosteroids

▪Considered the most effective medication class for controlling allergic rhinitis symptoms, such as congestion, rhinorrhea, and postnasal drip

▪Safe and are generally well tolerated

—Oral and intramuscular steroids

▪While oral and intramuscular corticosteroids are effective short-term treatments in severe allergic rhinitis, they are not appropriate for long-term use.

• Topical anticholinergics

—Ipratropium can reduce rhinorrhea in some patients but often has minimal effects on other nasal symptoms.

—Examples include oxymetazoline, pseudoephedrine, and phenylephrine.

—Nasal decongestants

▪Work well for short-term relief but should not be used at high doses regularly

▪If used consistently, can cause a rebound effect called “rhinitis medicamentosa”

—Oral decongestants

▪Can be beneficial as a short-term treatment

▪Caution should be used with consistent use of these medications due to side effects, including insomnia and hypertension

•Leukotriene antagonists

—Can improve rhinorrhea, sneezing, and pruritus in patients with allergic rhinitis

—Generally not recommended as first-line agents

—Often used if there is concomitant asthma