health

People with asthma have what are sometimes called “sensitized” airways.
Everyday factors that cause little or no trouble for most people can sometimes
cause people with asthma to have a flare-up or attack. These factors
are known as asthma triggers. There are two main kinds of triggers: allergic
and non-allergic triggers. An allergic trigger results from substances
called allergens*, which trigger an allergy. Examples of allergens that may
trigger asthma are pollens, molds, animal dander (small scales from fur
or feathers), dust mites*, cockroaches, and certain foods and medicines.
Most of these allergy-causing substances enter the body through the air
people breathe, but some are swallowed.
The second kind of asthma trigger is called an environmental or nonallergic
trigger. It has nothing to do with an allergy but causes the same
kind of reaction in the airways. Irritating substances in the air, such as
tobacco smoke, wood smoke, fresh paint, cleaning products, perfumes,
workplace chemicals, and air pollution can trigger or make asthma worse.
Other non-allergic triggers include cold air, sudden changes in air temperature,
exercise, heartburn, and infections of the airways, such as a cold
or the flu. Exactly which of these might trigger a reaction varies from
person to person.