Allergic Rhinitis

Allergic rhinitis, commonly known as hay fever or pollenosis, is a condition characterised by nasal inflammation due to airborne allergens. It is prevalent in approximately 20% of people in Western countries and is most commonly seen between the ages of 20 and 40.

The condition is often associated with other allergic disorders, including asthma, allergic conjunctivitis, and atopic dermatitis.

SEM Microscope image of Pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).

Signs and Symptoms

Illustration depicting inflammation associated with allergic rhinitis.

Allergic rhinitis presents with symptoms such as a runny or stuffy nose, sneezing, red, itchy, and watery eyes, and swelling around the eyes. Physical findings include conjunctival swelling and erythema, eyelid swelling with Dennie–Morgan folds, lower eyelid venous stasis (allergic shiners), swollen nasal turbinates, and middle ear effusion. Behavioural signs may include the "nasal salute" or "allergic salute," where individuals wipe their nose upwards with the palm, potentially leading to a transverse nasal crease.

Cause

The condition is triggered by environmental allergens like pollen, pet hair, dust, or mould. Predisposing factors include eczema, asthma, and certain genetic factors. Seasonal allergic rhinitis, or hay fever, is often caused by pollen from specific plants, whereas perennial allergic rhinitis is due to year-round allergens like dust mites or pet dander.

Diagnosis

Patch test.

Diagnosis typically involves a combination of clinical symptoms, skin prick tests, and blood tests for allergen-specific IgE antibodies. Skin testing is the most common method, which may include patch tests or intradermal tests. While these tests reveal specific allergies, they can sometimes yield false positives. For some patients, a diagnosis of local allergic rhinitis may explain symptoms despite negative systemic allergy tests.

Treatment

Prevention

Preventive measures include avoiding known allergens, using mite-proof covers on bedding, and maintaining a dry home environment. Early exposure to animals and growing up on a farm have been shown to reduce the risk of developing allergic rhinitis.

Medications

The primary goal of treatment is to reduce symptoms. Medications include:

• Nasal Steroids: Inhaled corticosteroids are effective for persistent symptoms but require consistent use for several weeks.
• Antihistamines: These can be taken orally or nasally to control symptoms like sneezing and itching. Second- and third-generation antihistamines are preferred due to fewer side effects like drowsiness.
• Decongestants: Used for nasal congestion but not recommended for prolonged use due to rebound congestion.
• Leukotriene Receptor Antagonists: Such as montelukast, can be used in cases where other medications are ineffective.
• Nasal Saline Irrigation: Helpful in both adults and children for symptom relief.

Allergen Immunotherapy

Allergen immunotherapy, or desensitisation, involves exposing the patient to increasing amounts of allergens to build tolerance. This can be administered subcutaneously or sublingually and is the only treatment that alters the disease mechanism.

Alternative Medicine

While some forms of complementary and alternative medicine like acupuncture have been looked at, there is insufficient evidence to recommend them for allergic rhinitis.

Epidemiology

Allergic rhinitis affects a significant portion of the population in Western countries, with a prevalence of 10-30% annually. The condition is most commonly diagnosed between the ages of 20 and 40.

History

The first accurate description of allergic rhinitis dates back to the 10th century by physician Abu Bakr al-Razi. In 1859, Charles Blackley identified pollen as the cause, and in 1906, Clemens von Pirquet elucidated the underlying mechanism of allergic reactions.

Self-assessment MCQs (single best answer)

What is the common name for allergic rhinitis?

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Which age group is most commonly diagnosed with allergic rhinitis?

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What are Dennie–Morgan folds an indication of?

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Which of the following is a common environmental allergen that triggers allergic rhinitis?

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What diagnostic method is most commonly used to identify specific allergies in allergic rhinitis?

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Which medication is preferred for long-term management of persistent nasal symptoms in allergic rhinitis?

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What is the primary goal of allergen immunotherapy?

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Which of the following is NOT typically recommended for controlling symptoms of allergic rhinitis?

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Which historical figure first accurately described allergic rhinitis?

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Which preventive measure has been shown to reduce the risk of developing allergic rhinitis?

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