Autumn and winter are dry and cold. The ambient temperature varies greatly from day to night, which may easily trigger lower respiratory tract allergic response in susceptible individuals. The airways of such individuals become inflamed and constrict in response to environmental stimulants, resulting in coughing, shortness of breath, production of phlegm, chest tightness and wheezing.
The cause of airway allergy is multifactorial and commonly results from interaction of 4 factors:
- Genetic – Allergic disease runs in family. The patient or his/her family member(s) usually have other allergic diseases such as eczema, allergic rhinitis, asthma or food allergy.
- Allergen stimulation – Common allergens are dust mites, pollens, grass pollens, cockroaches, molds and dog and cat dander. Some people may also be reactive to food that is extremely sweet, sour or cold.
- Environmental factors – Airborne stimulants such as cold air, air pollution, second-hand smoke and chemical smells. Others include rapid change in ambient temperature and humidity.
- Respiratory tract infection – Some childhood respiratory tract infections may predispose an individual to develop airway allergy and asthma later in life. Respiratory tract infection itself may trigger exacerbation of pre-existing allergic airway diseases.
Why does it get serious in cold seasons?
Besides dry weather and external stimulants, autumn and winter are the peak seasons for viral infection and influenza-like illness. Students may get cross-infected at school and spread the viruses to their communities, causing infection and allergic symptoms in susceptible people.
How to tell airway allergy from cold or flu?
The biggest difference is that a cold or flu patient would have fever and his/her condition would improve in 3 to 5 days after seeing a doctor. People with airway allergy would cough for 3 to 4 weeks. Their cough would be associated with chest tightness or wheeze. Their symptoms may disturb their sleep and limit their exercise capacity. Many people are diagnosed to have asthma with upper respiratory tract infection as the triggering event. On the other hand, people with mild asthma may notice that their symptoms become uncontrolled. In Hong Kong, around 70 to 90 people die from asthma each year, of which 20-30% were between 15-44 years old.
If one coughs for 3 weeks, he/she should seek medical advice and have imaging of the chest to rule out any other possibilities such as infection or rare lung problems. A simple lung function test known as spirometry will help to look for airflow obstruction and response to medication while the bronchial provocative test will occasionally be needed to confirm that the airway is more reactive (or sensitive) than normal individuals.
How to deal with airway allergy?
Stay away from allergens
- For dust mites, we should keep our bedroom clean and keep fluffy toys off the bed, and wash our beddings regularly with water at 60°C or above.
- For pollens, we should wear a mask and shut windows during pollen seasons. Air purifiers with HEPA filters will also help.
- For great changes in temperature, we should wear a mask or scarf and keep the air around our nose warm. We should keep ourselves well hydrated and breathe through our nostrils, avoid mouth breathing.
Control allergic rhinitis
Our nose is linked to the respiratory tract so if we could put allergic rhinitis under control, we could also stop airway allergy from aggravating, and vice versa. Asthma and allergic rhinitis should both be treated in order to obtain the best health benefits.
Take the right medication
Follow the doctor’s instructions on how to take medications, such as bronchodilator, leukotriene receptor antagonist and inhaled steroid. Patients should learn and be proficient in using the inhaler devices.
Avoid cold food and fruits
Cold air and chilled food can easily irritate the throat and trigger allergic airway response. Unless fruits are your allergens, you should eat them at room temperature, not from the fridge, to get vitamin C and fibre.
To some, crocodile soup is believed to improve airway allergy. There is not enough scientific evidence to proof or disproof such believe. Such soup causes no harm as long as one is not allergic to the ingredients of it. In fact, every airway allergy patient has his/her own profile of triggers or allergens. There is no need to follow others.
Dr Wong King Ying
Specialist in Respiratory Medicine
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