Allergic rhinitis is often caused by the body’s immune response to an environmental trigger. The Department of Otolaryngology at Singapore General Hospital (SGH) explains.
Allergic rhinitis is caused by the body’s immune response to an environmental trigger. Common triggers include house dust mites, pollen and airborne moulds. The
Department of Otolaryngology at
Singapore General Hospital (SGH), a member of the
SingHealth group, explains.
Symptoms of allergic rhinitis
These occur after exposure to the allergen. For example, walking into a dusty room may cause such symptoms to develop.
Other types of allergic rhinitis
Other less common types of rhinitis include:
1. Atrophic rhinitis
In atrophic rhinitis, the natural mucosal membrane is thinned out and the glands that secrete mucus and participate in mucus clearance are lost. This leads to secondary infections and persistent crusting of the nose.
This is a rare condition that occurs in those who have undergone aggressive surgery to the nasal cavities.
2. Vasomotor rhinitis
Vasomotor rhinitis is a condition where there is chronic rhinitis in the absence of an identifiable allergy.
Dilation of blood vessels in the nose is partly controlled by the autonomic nervous system. It is believed that an oversensitivity of this autonomic nervous system can cause vasomotor rhinitis. In some cases, the trigger may be a change of temperature or the presence of a chemical stimulant like strong perfume or chemical fumes.
How is allergic rhinitis diagnosed
There is often a history of other allergies and sensitive skin and some people may also have asthma. A
skin prick test may be able to identify the offending allergen (substance that triggers the allergic response). It is a simple test performed in the clinic.
In a skin prick test, a small area of skin, usually on the forearm is used to test for allergies to various allergens. A small amount of allergen is then applied to the skin and the area observed for a positive reaction.
By identifying the allergen, severe or recurrent attacks can be reduced by avoiding or minimising subsequent exposure to the allergen. Common allergens include dust mites and pollen.
Treatment for allergic rhinitis
Treatment of allergic rhinitis is aimed mainly at reducing the severity and frequency of attacks. Methods of management can be divided into :
Changes to the living environment will have to be made to avoid the allergens that trigger attacks. For example, frequent cleaning of living areas and replacing items such as carpets or stuffed toys may reduce the amount of exposure to dust mites in the house.
Medical therapy is directed at controlling symptoms and reducing the allergic response.
In cases where symptoms are intermittent, antihistamines may be prescribed. Where attacks are frequent, a nasal steroid may also be added. Nasal steroids are widely used because they are effective for long-term control of symptoms and are safe for long-term use as they have a topical action and very little of the steroid actually gets absorbed by the body.
Surgical therapy may be useful where there are anatomical abnormalities such as a deviated nasal septum, or inferior turbinate hypertrophy.
Surgery may improve the symptoms of congestion and blockage, but may not have any impact on the other symptoms such as runny nose or itchy eyes. Nasal steroids may still have to be used to control these symptoms.
It is also suitable for a select group of people with severe, prolonged symptoms that do not respond to conventional therapy.
In immunotherapy, the body’s immune system is modulated to reduce the response to the allergen, thus reducing the severity of symptoms. This is a slow process and will require injections or self-administered drops taken regularly over a period of 1 to 3 years.
See the next page to learn
what is sinusitis and how it differs from allergic rhinitis.