Allergic diseases are on the rise all over the world. These include rhinitis, food allergies, drug allergies, and eczema. In collaboration with immunology and allergy specialist Dr. Adrian Wu 鄔揚源醫生, Healthy Matters is bringing you the ultimate guide to common allergies in Hong Kong.
What are allergies?
Before we go into the allergy landscape in Hong Kong, let’s just step back for a minute and talk about allergies themselves. At their most basic, allergies are an immune reaction to a harmless food or substance.
The prevalence of allergies in Hong Kong
Allergies are common across the world and Hong Kong is no different. Allergies are more common in children as some people grow out of their allergies. A global study in 2002 found that roughly one in three children in Hong Kong suffer from asthma, allergic rhinitis and/or eczema. In another study, 42.9% of Hong Kong-born children were sensitive to environmental allergens. There is little research on the prevalence of food allergies in Hong Kong but one questionnaire amongst Hong Kong parents found that 8.1% of Hong Kong 2-7-year olds had experienced adverse food reactions – the most common reactions were to shellfish, milk and eggs.
Common environmental allergens in Hong Kong and how to reduce them
With our tight urban quarters, people in Hong Kong are more likely to suffer year-round from allergies rather than seasonal allergies such as hayfever. The most common symptoms of environmental allergens are rhinitis, asthma, and eczema.
The following are the most common environmental allergens in Hong Kong:
1 – House dust mites are the most common allergen in Hong Kong. The allergen is actually the dust mite feces while cause a range of symptoms including eczema, allergic rhinitis and asthma. House dust mites thrive in a humid environment that is around 20 to 25 degrees. Sound familiar? Sounds like the conditions inside most Hong Kong houses to us. Dust mites live, as you can guess, in the dust in our house, usually made up of the dead skin cells we shed. They’re found in fabric such as bedding, upholstery, clothing, carpets, etc. Between 100 and 500 live in every gram of dust. To rid your house of dust mites and control dust mite allergens, there are a few suggestions:
- The first step is to reduce household humidity. Sometimes reducing household relative humidity to below 50% for 5 days can do the trick.
- Cover your bed and pillows with allergen-proof covers.
- Either avoid using thick carpets at home or use a vacuum compatible with a HEPA filter.
2 – Animal dander is the second most common indoor allergen in Hong Kong. Dander is the material shed from the body of animals that have fur, hair, or feathers. A lot of animals with fur will cause an allergy but cat dander seems to be the most potent. A lot of the recommendations for animal dander are the similar as for dust mites. If removing the animal from your environment is not possible, also ensure the animal is washed 2-3 times per week.
3 – Fifteen to twenty percent of asthma or allergic rhinitis sufferers are to allergic to cockroaches. You think that’s the gross part? Cockroach allergens are found in cockroach feces, saliva, secretions and sloughed-off skin and become part of household dust. To control cockroaches in your house, the following is recommended:
- Use cockroach traps in mild infestations or professional pest control if your house is heavily infested.
- Store food in sealed containers and keep kitchens clean of oil stains and soap residue.
Food allergies in Hong Kong
Like environmental allergies, food allergies cause your immune system to react to otherwise harmless substances. Food allergies can be challenging to track as reactions can show up anytime from within a few minutes to a few weeks later. Often the symptoms are fairly mild so people may not suspect an allergy and go undiagnosed. The eight most common food allergies in Hong Kong are crustacean seafood, chicken eggs, cow’s milk, fish, wheat, soy, peanuts and tree nuts. Seafood is by far the most common and severe allergen in Hong Kong – of those with severe, life threatening allergies, 70% will have a seafood allergy. The best way to control food allergies is to avoid the allergenic food altogether.
Allergy symptoms range from the mildly annoying to the life threatening. Common reactions include the following grouped symptoms, though you may not only experience one:
- Allergic rhinitis – sneezing and an itchy, runny or blocked nose
- Conjunctivitis – itchy, red, watering eyes
- A cough, wheezing, chest tightness and/or shortness of breath
- Hives – a raised, itchy red rash
- Stomach pain, nausea, vomiting and/or diarrhea
- Eczema – dry, red and cracked skin (see more about baby eczema in Hong Kong here)
- Swollen tongue, eyes, face, and/or lips
Anaphylaxis is a medical emergency that requires immediate attention
It is a very rare allergic reaction but can be life threatening. It shows up within minutes of exposure and affects the entire body. In addition to the symptoms above, anaphylaxis symptoms include:
- Blue skin and/or lips
- Collapsing and losing consciousness
- Swelling of the throat and mouth
- Difficulty breathing
When should you seek medical assistance for allergies?
If you suspect an allergy in yourself or your child, visit a doctor to discuss how to manage it and the possibility of allergy testing.