Nasal Allergy
(Allergic Rhinitis Singapore)

Allergic Rhinitis Singapore

Nasal allergy or allergic rhinitis in Singapore is a common health problem. It may be seasonal, meaning that it causes symptoms only at certain times of the year. More commonly in Singapore, it is perennial, meaning that it causes symptoms all year long. Other health problems, such as asthma and eczema, often occur together with allergic rhinitis.

What is Allergy?

allergic-rhinitisAn allergy is an exaggerated response to certain substances, which in most individuals, result in no symptoms. Allergy is the name given to the way your body reacts when it mistakes ordinary harmless substances (for example pollen, house dust mites, cat / dog fur) for something harmful.


Statistics show that up to 1 in 5 Singaporeans may suffer from some form of allergy. For most, allergies are a short-lived nuisance that affects quality of life. However, for some, allergy can be a life-threatening disease.

Allergic symptoms appear when the body’s immune system begins to respond to a substance it believes may be harmful (allergen). The immune system sends defenders called antibodies to the entry site of the allergen, which results in a release of chemical compounds such as histamine directly into the bloodstream. These chemical compounds produce the symptoms that we feel. These symptoms can range from nasal stuffiness, nasal congestion and itchy eyes. Some patients may also experience hoarseness, cough and sore throats. 


Other less common symptoms include swelling of the tissues in the face or throat, skin irritation and even respiratory problems and asthma flare-ups.

What Are Allergens?

Allergens are substances which are more prone to generate an allergic response in humans. Pollens, food, dust, animal dander, chemicals and certain medications are examples of allergens. Certain allergens such as dust and pet dander are always present in our surroundings, and are referred to as perennial allergens.

What Is A Nasal Allergy?

The medical term for a nasal allergy is allergic rhinitis, which is more commonly known colloquially as a ‘sinus problem’. Symptoms of a nasal allergy include an itchy and runny nose, sneezing and nasal congestion. Allergic rhinitis was previously also known as ‘hay fever’.

What Is Allergic Conjunctivitis (Eye Redness / Irritation)?

allergic-conjunctivitisThe conjunctiva is a thin membrane which covers the eye and part of the inside of the eyelids. Irritation of the conjunctiva causes your eyes to become swollen and red, which is referred to as conjunctivitis.


Allergic conjunctivitis is a form of conjunctivitis which is related to allergic rhinitis, and is caused by an allergen. As described above, such allergens include pollen, dust and animal dander. Good control of allergic rhinitis generally reduces the incidence of allergic conjunctivitis.

What Is Dust Mite Allergy?

Dust mite allergy is highly prevalent in Singapore. There are 3 common types of dust mites, namely:

  • Dermatophagoides pteronyssinus (Der.P)
  • Dermatophagoides farinae (Der.F)
  • Blomia Tropicalis (B.Tropicalis)


These dust mites are tiny cannot be seen with the naked eye. They live off dead skin and are present throughout the house. Dust mites eat the dead skin and then leave their droppings behind, which contains their stomach enzymes. It is these stomach enzymes that incite an allergic response in humans.

Dust mites love warmth, humidity and dead skin. The ideal place for them to breed is in a bedroom, where there is lots of fabric such as thick curtains, carpet, bedding and cuddly soft toys. In general, the female dust mite lays up to 50 eggs within 3 weeks, and each egg takes about three to four weeks to reach adulthood. The lifespan of a dust mite is about 10 weeks, and each female would have laid between 40 to 80 eggs within a period of about 6 weeks. Furthermore, 1 gram of dust can contain as many as 1,000 dust mites. This same gramme can contain 250,000 faecal pellets that are much smaller and lighter than dust mites.


How do I get rid of Dust Mites?

Although killing mites is initially very desirable, if dust is left in place, the mites will soon return. It is thus important to clean regularly and thoroughly to minimize dust.

  • Floors: Carpets are an ideal place for dust to settle and mites to hide. The ideal situation would be to minimize carpets in the house; but if this is not possible, a short pile carpet and regular vacuuming with a HEPA-filter vacuum cleaner would be the next best alternative.
  • Curtains: Wooden blinds or plastic curtains are preferred over heavy fabric curtains.
  • Bedding / Mattresses: All bedding should be washed at least weekly in temperatures above 60 degrees centigrade and above to kill dust mites. Mattresses harbor a lot of dust and dead skin cells, and should be vacuumed regularly. Anti-dust mite covers for mattresses and pillows are available and can be used to stop the mites from getting out. These covers also need to be washed regularly at a similar temperature to bedding.
  • Furniture: Upholstered furniture traps dust. Better alternatives would be plastic, wood or leather furniture.
  • Soft toys: These, like bedding, can harbor a large amount of dust mites. The best thing would be to get rid of them completely, but an alternative would be to regularly wash them at 60°C to kill the dust mites.

Dust mites and their droppings generally cling to bedding / carpet / heavy fabrics and are not circulating in the air. Air purifiers clean circulating air and thus in general, are not useful in patients with dust mite allergies and allergic rhinitis.

Over-The-Counter (OTC) Medications For Allergies

Medications for allergic rhinitis, sinus congestion, runny nose and the common cold make up the largest section of OTC medication in pharmacies. When used appropriately, most of them provide significant relief of symptoms from allergies and common colds. These medications do not cure the allergies or the common cold, but help relieve the symptoms making the patient more comfortable.



Antihistamines are one of the most widely used medications on the market, due to their high efficacy and ease of administration. Histamine is a chemical in the body that is responsible for the majority of the congestion, sneezing and runny nose that a patient suffers with an allergic attack. Antihistamines block the action of histamine and thus reduce the allergic symptoms. For best results, antihistamines should be taken before histamine has been released in the body; i.e. before allergic symptoms are well established.

There are numerous antihistamines available over the counter, such as Telfast, Clarityn, Clarinase, and Zyrtec



The majority of antihistamines are non-drowsy, but some older antihistamines may result in drowsiness. Caution has to be taken when driving or operating heavy machinery.




Nasal congestion or obstruction is typically due to swollen or expanded blood vessels in the nose and air passages. The nose has an abundance of these blood vessels with a great capacity for expansion. Histamine can stimulate these blood vessels to expand.

Decongestants are useful in this case as they case shrinkage of these blood vessels, which forces the blood out and open up the air passages. Decongestants usually come in two forms, an oral formulation and a nasal spray. Examples of oral decongestants include Phenylephrine and Pseudoephedrine, and examples of nasal spray decongestants include Afrin and Oxy-nase. These are chemically related to adrenaline, which is a form of stimulant. Hence, decongestants have side effects such as agitation and nervousness, and can also elevate blood pressure and pulse rate. In patients who are elderly, they may also cause urinary retention. These side effects are more pronounced in patients who take the oral formulation. Decongestants should not be used by patients with irregular heart rhythms, high blood pressure, heart disease or glaucoma.


Combination Antihistamine-Decongestant

Numerous combinations of antihistamines with decongestants such as Zyrtec-D, Telfast-D, Claritin-D  and FEDAC are available. These medications  are convenient, and are most useful in patients with symptoms of runny nose and nasal congestion.


Nasal Sprays

Nasal steroid sprays are now available over the counter, and are used for chronic nasal inflammation and congestion from allergies and other causes. There has been some evidence that starting a nasal steroid spray, even in cases of the common cold, may be effective in reducing the duration and severity of symptoms. Examples of such nasal steroid sprays include Flixonase, Nasonex, Avamys and Nasacort.

Allergy tests are used to determine what allergens a person may be sensitive (allergic) to. The more common methods are:

  • Skin prick tests
  • Blood tests (RAS test)
  • Food elimination and challenge tests

Skin Prick Tests

Skin-prick-testSkin prick tests are the most common method of allergy testing. The test involves placing a small amount of suspected allergy-causing substances on the skin, usually on the forearm, upper arm or back. Then, the skin is pricked so the allergen goes under the skin’s surface. Results are usually seen after 20 minutes, and several substances can be tested for at the same time.

Skin prick tests are most useful for diagnosing aeroallergens such as dust, pollen, mold and others that cause allergic rhinitis and asthma. In certain cases, the skin prick test may also be used to diagnose food allergies.


Blood Tests

Blood tests can be done to measure the total amount of immunoglobulin (IgE) in the blood as well as IgE to specific allergens. This test may be useful when skin testing is not helpful or cannot be performed for certain medical reasons.


Food Elimination and Challenge Tests

An elimination diet can be used to check for food allergies. It refers to a diet in which foods that are suspected to cause symptoms are removed from the diet for several weeks, and then slowly re-introduced one at a time while the individual is observed for a sign of an allergic reaction. This must be done carefully in individuals with suspected severe reactions to foods.

Allergy Treatment (Immunotherapy)

sublingual immunotherapyImmunotherapy is the only treatment that can provide long lasting relief or cure from allergies. The aim behind immunotherapy is to build up the patient’s immunity to a particular allergen, thereby reducing the chance of developing symptoms after exposure. There are currently two methods of administering immunotherapy:

  • Subcutaneous 
  • Sublingual

Subcutaneous Immunotherapy

Subcutaneous immunotherapy (SCIT) has been a proven allergy treatment for more than 100 years. They are the only treatment that changes the immune system. They prevent new allergies and asthma from developing and have a lasting beneficial effect, well after therapy has been completed.


Sublingual Immunotherapy

Sublingual immunotherapy (SLIT) is a newer form of immunotherapy. Instead of injecting an allergen under the skin, small doses in the form of drops (allergy drops) are administered under the tongue.

Allergy drops have been used around the world for more than 60 years, and many studies show that allergy drops are safe and effective. Dosing levels and the route of administration are safe enough to effectively treat infants, children, and people suffering from chronic conditions that previously made them unable to receive immunotherapy via shots. In fact, the World Health Organization has endorsed sublingual immunotherapy as a viable alternative to injection therapy.


The well-respected Cochrane Collaboration, the world’s most-trusted international organization dedicated to reviewing healthcare treatments, recently concluded that immunotherapy significantly reduced allergy symptoms, use of allergy medications and improved control of allergic rhinitis.

There are two types of SLIT – tablets and drops. The tablet form is effective only against house dust mites, whereas the droplet form can be effective against a multitude of different allergens. 


There are many advantages and disadvantages of SLIT vs. SCIT, as well as tablet vs. droplet form. Please contact us for further discussion regarding your potential options for treatment