Nasal Allergy / Allergic Rhinitis: The Facts

by Dr. Kenny Pang
The science behind nose allergies and their annoying symptoms, and why allergic rhinitis should be properly managed.

Rhinitis is the inflammation of the nasal mucosa (lining of the nose), which brings on symptoms like sneezing, nasal congestion (blocked nose), nose itch, and runny nose. It can be triggered by the common cold (viral infection), but nose allergy is the most common cause of rhinitis.

Allergic rhinitis, also known as nose or nasal allergy, affects 10-30% of the global population. In Singapore, it is estimated that 24% of our population suffers the uncomfortable condition.  

Nasal allergy symptoms can affect other organs besides the nose.

With allergic rhinitis, the inflammation may involve not only the nasal mucosa but also the eyes, ears, sinuses, mouth, and throat. 

The nose lining may be swollen and cause the nasal passage to narrow, causing symptoms like difficulty in breathing and nasal congestion (blocked nose). Other symptoms and signs of allergic rhinitis include runny nose, sneezing, nose itch, redness, tearing, swelling, ear pressure (a sensation of fullness in the ear), and postnasal drip (which can make you feel like you constantly need to clear your throat). Most people with nasal allergy also have watery and/or itchy eyes. Throat symptoms include persistent phlegm, recurrent sore throat, and chronic cough. 

People with allergic rhinitis tend to have “allergic shiners”, which refer to dark circles around the eyes, resulting from vasodilation (pooling of blood under the eyes) and nose congestion (swelling of tissues in the nasal cavities).

Another feature seen on people with allergic rhinitis is the “nose crease”, a horizontal line that forms across the lower half of the nose bridge when one repeatedly rubs the nose upwards using the palm of the hand. Physicians dub this gesture as the “allergic salute”, because people with allergic rhinitis do this habitually in response to their nasal discomfort. 

Allergic rhinitis is an immune response.

In terms of immunology, allergic rhinitis is due to a complex interaction of inflammatory proteins triggered by antibodies known as immunoglobulin E (IgE). The inflammation of the nasal lining is a mediated response to an allergen, that is, a protein that can cause an allergic reaction. The tendency to develop this allergic (IgE-mediated) reaction to allergens has a genetic component. In other words, it can be hereditary. Allergy testing can help identify specific allergy triggers.

In allergic individuals, exposure to certain foreign proteins (allergens) leads to “allergic sensitisation”, where the immune system produces specific IgE that are directed against these proteins. When the allergen, such as a specific pollen grain or dust mite, is inhaled into the nose, it binds to the immunoglobulin (IgE) on the mast cells (allergic cells), and triggers the release of allergic mediators. These mediators, including chemicals like histamine, then cause the lining of the nose to become inflamed and produce excess mucus. This leads to the symptoms of runny nose, nose congestion, sneezing, nose itching, redness, tearing, swelling, ear pressure, and postnasal drip.  

The allergic response has two main phases: the immediate phase and the delayed phase. Usually occurring within 20 to 30 minutes of exposure to the allergen, the immediate reactions in the nose induce acute allergy symptoms, such as nose itch, clear nose discharge, sneezing, and nose congestion. The late-phase reaction may occur hours later.

Allergic rhinitis may be linked to other co-existing problems.

Allergy of the nose can be associated with several co-morbid conditions, including asthma, atopic dermatitis (eczema or skin allergy), and nose polyps (swellings in the nose).

According to the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines, the development of allergic rhinitis (nose allergy) and the development of asthma have been shown to be related. In fact, the two conditions are manifestations of one syndrome in two parts of the respiratory tract.  

Research has found that people with allergic rhinitis have a higher risk of developing bronchial asthma. It is well accepted that allergic rhinitis may precede the onset of asthma symptoms; and that asthma will not be optimally controlled unless the allergic rhinitis is also effectively managed.  

People with allergic rhinitis may also have sleep problems. Studies show that the more severe the nasal allergic symptoms, the poorer quality their sleep is. Allergic rhinitis has also been linked to the sleep disorder, obstructive sleep apnea / apnoea (OSA).

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