Explainer | What you need to know about allergies – their causes, symptoms, treatment, and ways to avoid them; a specialist explains

Dr Adrian Wu says allergy ‘season’ differs depending on climate and environment; in Hong Kong, the onset of high humidity heralds dust-mite breeding

While pollen is a cause of allergies in parts of the world, dust mites are the bigger problem in Hong Kong; dehumidifiers and hot water are weapons of choice

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In many parts of the world, spring is the start of pollen season, which triggers allergies. An allergy specialist in Hong Kong describes the allergy situation in the city in this brief explainer – what causes them, allergy symptoms, how to treat allergies and how to avoid them. Photo: Shutterstock

Published: 7:15pm, 18 Apr 2024Updated: 9:27am, 20 Apr 2024

Spring season is in full bloom in many parts of the world, including North America and Europe. While many people admire the flowering trees, those who suffer allergies are blowing their noses, scratching their eyes and sneezing.

As one who rarely goes anywhere without eye drops and antihistamine tablets, I understand the misery of environmental allergies; it can be very hard to avoid them. I have suffered from hay fever most of my life: the itchy eyes and streaming nose signal that something close to me is raining plant pollen.

What causes allergies?

An allergy occurs when the body’s immune system perceives a substance, like pollen, as harmful – even though it is harmless to most people – and overreacts to it, the Asthma and Allergy Foundation of America explains.

An allergy occurs when the body’s immune system perceives a substance, like pollen, as harmful and overreacts to it. Photo: Shutterstock

Those substances – allergens – can also include dust mites, pet dander, insects, ticks, moulds, foods and some medications. Allergens tend to invade and irritate the airways, eyes, skin – and lungs, in the case of allergic asthma.

Hong Kong-based specialist in immunology and allergy Dr Adrian Wu notes that the pattern of allergy seasons across continents is diverse, and depends on climate and environmental conditions. Hong Kong, a small place, tends to be more homogeneous.

The most common cause of allergies here, says Wu, is the house dust mite, which lives in bedding, clothing and soft furnishings including carpets, curtains, pillows and duvets. The cause is proteins in dust-mite droppings, and – later – the dead mite carcasses.