Allergic Rhinitis
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Introduction
Allergic rhinitis is an inflammation of the nasal mucosa triggered by an allergic reaction. It affects 40% of children and 20-30% of adults, and prevalence has increased developed countries, particularly in the past two decades.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Causes and Risk Factors
Allergic rhinitis can be classified as seasonal or perennial. Seasonal allergies occur during a specific time of year and usually occur in response to outdoor allergens, such as tree, grass, and weed pollens, or airborne moulds.
Perennial allergies occur throughout the year, though can vary in severity. Common allergens include dust mites, animal dander, and moulds.
Pathophysiology
Increased IgE levels in response to specific allergens lead to excessive degranulation of mast cells. This release of histamine and inflammatory cytokines leads to local inflammatory reaction in the airways.
Signs, Symptoms, and Diagnosis
- history
- physical exam
History
It is important to identify allergens by taking an environmental/occupational history.
Ask about related conditions such as atopic dermatitis, asthma, sinusitis, and family history.
Physical Exam
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
Differential Diagnosis
Differential diagnosis includes:
- acute viral infection
- vasomotor rhinitis
- deviated septum
- nasal polyps
- acute/chronic sinusitis
- drug-induced rhinitis
- pregnancy
Treatments
The most important aspect of management is mimimizing exposure to allergens.
Medications
Oral antihistamines are the first line for mild symptoms.
Intranasal decongestants can be very effective, but their use must be limited to 3-5 days to avoid rhinitis medicamentosa, or rebound nasal congestion.
Intranasal corticosteroids can be used for moderate/severe or persistent symptoms.
Allergy skin testing
Skil testing can be done to identify allergens
Immunotherapy (allergy shots)
Immunotherapy consists of periodic (ie weekly) subcutaneous injections of custom solutions containing one or more antigens to which the patient is allergic.
Consequences and Course
Resources and References
Topic Development
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