Allergic Rhinitis (Hay Fever) – Seasonal and Perennial

Hay fever is a common ailment characterized by recurrent sneezing, runny nose, nasal congestion and watery eyes and affects millions of people globally. There is often a misconception, largely due to the term ‘hay fever’, that it is caused and solely due to pollen and other botanical irritants. However, hay fever is one presentation of a constitutional immune-mediated hypersensitivity known as atopy, that is also responsible for other allergic conditions like allergic asthma and atopic dermatitis. Hay fever is more correctly known as allergic rhinitis. It can be either seasonal or perennial and must be differentiated from non-allergic rhinitis.

What is allergic rhinitis?

Allergic rhinitis is the inflammation of the nasal lining due to an immune-mediated hypersensitivity (allergies). The nasal cavity is lined by a thin mucosal epithelium that secretes mucus to trap dust and microbes and keep the lining moist since it is prone to drying due to the constant airflow. It is highly sensitive to various stimuli but this is largely a protective mechanism that comes into effect in response to smoke, dust and other irritants.

Causes of Allergic Rhinitis

In some people, a defective immune mechanism causes inflammation of the nasal lining which may be unrelated to any threat. The underlying cause is a defective immune response which is often inherited and various factors may trigger the condition, including :

  • Pollen
  • Animal hair/fur
  • House dust mite
  • Cockroaches
  • Smoke

The triggers are not the cause of the condition. Allergic rhinitis must be differentiated from non-allergic rhinitis which is not associated with immune-mediated hypersensitivity. Non-allergic rhinitis can be infectious (common) or non-infectious. One of the more common causes of infectious rhinitis is the common cold (viral infection). A person with allergic rhinitis is more prone to these types of infections which is responsible for acute exacerbations but the underlying cause of the chronic hay fever is an allergic response.

Seasonal and Perennial Allergic Rhinitis

Allergic rhinitis may be persistent throughout the year in which case it is known as perennial allergic rhinitis or only arise at certain times of the year (seasonal). People with perennial rhinitis tend to experience exacerbations during certain seasons although the symptoms are present on most days of the week throughout the year. On the other hand, a person with seasonal rhinitis is sensitive to various trigger factors throughout the year but the clinical features are most prominent in certain seasons like spring where there is a high pollen count.

Signs and Symptoms

Inflammation of the nasal lining gives rise to the typical signs and symptoms seen in allergic rhinitis, including a runny nose, sneezing, itchy nose and nasal congestion and may extend to surrounding areas thereby presenting with watery, itchy and red eyes, sore throat and a shallow cough.

Most of the mucus produced by the nasal lining is emptied at the back of the throat. When there is excessive mucus production, as is the case with allergic rhinitis, post-nasal drip may arise. This causes additional symptoms like a hoarse voice, in addition to the nasal tone of the voice seen with rhinitis, sore throat and persistent cough and predispose a person to respiratory tract infections.

A characteristic feature of allergic rhinitis is exacerbation at certain times of the day – itchy eyes and nose at night, with morning bouts of sneezing and a runny nose. With acute exacerbations or in seasonal rhinitis, these symptoms are persistent throughout the day and night.

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