Allergic Rhinitis

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.

Differential Diagnosis

•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.

•Allergy testing is often required to differentiate allergic from nonallergic forms of rhinitis (see Table 29-1).

Courtesy of David Stukus, MD.

Diagnostic Considerations

•Two elements are often necessary to establish the diagnosis of allergic rhinitis.

—Symptoms consistent with allergic rhinitis

—Positive skin test results or serum IgE test results for seasonal and/or perennial aeroallergens, which need to correlate with the clinical history

• The diagnosis can also be assigned with a strong clinical history associated with known exposures, such as

—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.

• Decongestants

—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

•Common medications used to treat allergic rhinitis are discussed in Table 29-2.

Table 29-2. Common Medications Used to Treat Allergic Rhinitis
Drug Type	Common Examples	Discussion
Antihistamines
First-generation H1-antihistamines	Diphenhydramine, chlorpheniramine	Effective agents for rhinitis symptoms but often limited by side effect profilesSide effects can include sedation, dry eyes, dry mouth
Second-generation H1-antihistamines	Loratadine, fexofena-dine, cetirizine	First-line therapy for rhinitisInexpensive and safeSafe for long-term use, given the side effect profile
Intranasal antihistamines	Azelastine, olopatadine	Used as an add-on therapy in allergic rhinitis and often effective in other types of rhinitis, such as nonallergic rhinitis
Corticosteroids
Topical (intranasal) corticosteroids	Beclomethasone, budesonide, ciclesonide, flunisolide, fluticasone furoate, fluticasone propionate, mometasone, triamcinolone	Intranasal corticosteroids are an effective medication class for controlling symptoms of allergic rhinitisThe regular use of intranasal corticosteroids is generally preferred over as-needed useSome agents are approved for use as in patients as young as 2 y of age
Leukotriene blockers
	LTRAs: montelukast, zafirlukast5-LO inhibitor: zileuton	Not a first-line treatment for rhinitis but can have a role as an add-on therapyLTRAs are generally preferred over 5-LO inhibitors, given that liver function needs to be monitored with 5-LO inhibitorMontelukast is approved in patients as young as 6 mo of ageZafirlukast is approved in patients ≥5 y of ageZileuton is approved in patients ≥12 y of age
Decongestants
	Oxymetazoline, phenylephrine, pseudoephedrine	While these agents work well for short-term relief of congestion, they should not be used long-term, given the side effect profileMedications such as oxymetazoline are approved in children ≥6 y of age

LTRA, leukotriene receptor antagonist; 5-LO, 5-lipoxygenase

•Other treatments for allergic rhinitis

—Environmental controls

When a sensitivity to an aeroallergen has been established via a history, skin testing, and/or serum IgE testing, then efforts should be made to decrease exposure to specific aeroallergens.

Environmental controls can be effective in decreasing symptoms due to perennial allergens, such as dust mites, pets, and cockroaches.

For those with known pollen sensitivities, caution should be taken with outdoor activities when pollen counts are high.

—Immunotherapy (subcutaneous and sublingual)

Allergen immunotherapy may be considered for patients with allergic rhinitis and documented allergic sensitivities to aeroallergens with an appropriate history.

Allergen immunotherapy is the only treatment that has been shown to alter the underlying immune response to aeroallergens.

Treating Associated Conditions

•Allergic conjunctivitis

—Manifests with ocular pruritus, erythema, and discharge when exposed to sensitized aeroallergens

—Treatment options

Oral H₁-antihistamines

Nasal steroids (in many patients, nasal steroids can improve ocular symptoms)

Topical (eye drops) antihistamines and/or mast cell stabilizers

~Olopatadine, bepotastine, azelastine, epinastine (prescription only

~Ketotifen (nonprescription)

Immunotherapy (allergy shots)

•Allergic asthma (Please see the chapters on asthma)