Overview

When you have asthma, certain things can make your symptoms worse. These things are called triggers.

Things that you're allergic to can trigger your asthma. They may include:

• Dust.
• Dust mites. These are tiny, nearly invisible creatures. They live in bedding, carpet, and furniture.
• Cockroach droppings.
• Pet dander. Dander is loose skin cells (like dandruff) from dogs and cats.
• Indoor mould.
• Pollen.

Your asthma can be triggered by other things too, such as:

• Colds, influenza (flu), and sinus infections.
• Cigarette smoke, air pollution, and fumes from gas, oil, or kerosene heaters.
• Exercise. Many people have symptoms when they exercise.
• Dry, cold air.
• Medicines, such as aspirin or beta-blockers.
• Hormones, including those involved in pregnancy and menstrual periods. A woman's symptoms may change just before or during her period.